is Jeremie Averous and Thierry Linaresn rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In that “elastic global analysis should be based on the
assumption that the stress-strain behaviour of the material is linear, whatever the stress level is”.
The supplementary rules for stainless steel give no additional information for the global analysis
of stainless steel structures, though an analytical expression for the description of the rounded
stress-strain response of stainless steel based on the two stage Ramberg-Osgood model [4,5,6] is
given in Annex C [1].This paper assesses whether the assumption of an elastic global analysis is
sufficient or whether, due to the significant nonlinearity of stainless steel, a plastic global analysis
is necessary. E
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-1-
4 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-1-
4 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-1-
4 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN
1993-1-4 does not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1993-1-1 states that global second order effects may be neglected if the critical
load factor of the frame cr is greater than or equal to 10 for an elastic analysis, or greater than or
equal to 15 when a plastic global analysis is used. No specific guidance is provided in EN 1993-14 for the design of stainless steel frames, for which the nonlinear stress-strain behaviour of the
material will result in greater deformations as the material loses its stiffness. A study of the
effects of material nonlinearity on the stability of stainless steel frames is presented herein. A
series of different frame geometries and loading conditions are considered. Based on the findings,
proposals for the treatment of the influence of material nonlinearity on the global analysis and
design of stainless steel frames are presented. Keywords Continuous Strength Method, Frame
stability, Global analysis, Numerical modelling, Second order effects, Stainless steel 1 Introduction
Stainless steel is widely used across a range of industries with its key advantage over ordinary
carbon steel being its corrosion resistance and durability. Although a number of design standards
for stainless steel currently exist, their provisions have generally been based on a presumed
equivalence with the carbon steel design rules. However, stainless steel and carbon steel have
distinctly different material characteristics; while carbon steel is accurately characterised by a
bilinear (elastic, perfectly plastic) stress-strain response, stainless steel exhibits nonlinear rounded
stress-strain behaviour with no sharply defined yield point. It is important that the codes reflect
these differences so as to ensure safe, efficient, and structurally sound design. The current
European rules for global analysis and design are examined in this paper, assessing whether the
methods provided are suitable for stainless steel. Particular attention is given to the extent to
which the differences between the behaviour of stainless steel and carbon steel frames are
adequately recognised. EN 1993-1-4 [1] gives supplementary guidance for the design of stainless
steel structures that complement the design rules given for structural carbon steel in EN 1993-1-1
[2]. Section 5 of EN 1993-1-1 outlines the rules for structural analysis with detailed subsections
on structural modelling, global analysis and imperfections, as well as methods of analysis
considering material nonlinearities. The guidance on material nonlinearities largely relates to the
occurrence of traditional idealised plastic hinges, as seen in carbon steel structures. However,
such hinges do not form in stainless steel structures; instead zones of plasticity with gradually
reducing stiffness, but with peak capacities well in excess of the traditional plastic moment are
exhibited [3]. EN 1993-1-1 also states that “elastic global analysis may be used in all cases” and
that “elastic global analysis should be based on the assumption that the stress-strain behaviour
of the material is linear, whatever the stress level is”. The supplementary rules for stainless steel
give no additional information for the global analysis of stainless steel structures, though an
analytical expression for the description of the rounded stress-strain response of stainless steel
based on the two stage Ramberg-Osgood model [4,5,6] is given in Annex C [1].This paper assesses
whether the assumption of an elastic global analysis is sufficient or whether, due to the
significant nonlinearity of stainless steel, a plastic global analysis is necessary. EN 1993-1-4 does
not provide global plastic design rules for indet
Abstract a , L. Gardner a a , E. Real b , I. Arrayago Imperial College London b b , D.A. Nethercot
Universitat Politècnica de Catalunya a In structural frames, second order effects refer to the
internal forces and moments that arise as a result of deformations under load (i.e. geometrical
nonlinearity). EN 1