AS 2327.1—2003
AS 2327.1
Australian Standard™
Composite structures
Part 1: Simply supported beams
This Australian Standard was prepared by Committee BD-032, Composite
Construction. It was approved on behalf of the Council of Standards Australia on
3 June 2003 and published on 18 August 2003.
The following are represented on Committee BD-032:
Association of Consulting Engineers Australia
Australian Building Codes Board
Australian Steel Institute
Bureau of Steel Manufacturers of Australia
Institution of Engineers Australia
Steel Reinforcement Institute of Australia
University of New South Wales
University of Adelaide
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This Standard was issued in draft form for comment as DR 99100.
AS 2327.1—2003
Australian Standard™
Composite structures
Part 1: Simply supported beams
Originated as AS 1480 Supplement 1—1974.
Previous edition AS 2327.1—1996.
Third edition 2003.
COPYRIGHT
© Standards Australia International
All rights are reserved. No part of this work may be reproduced or copied in any form or by any
means, electronic or mechanical, including photocopying, without the written permission of the
publisher.
Published by Standards Australia International Ltd
GPO Box 5420, Sydney, NSW 2001, Australia
ISBN 0 7337 5338 8
AS 2327.1—2003
2
PREFACE
This Standard was prepared by the Standards Australia Committee BD-032, Composite
Construction, to supersede AS 2327.1—1996 Composite structures in structural steel and
concrete, Part 1—Simply supported beams.
This revision incorporates a number of technical and editorial changes. The principal
differences are briefly outlined in the following:
1
Shear connectors:
(a)
The value of the density reduction factor (k r), used in the calculation of the
design shear capacity (f ds) of shear connectors with lightweight concrete, has
been changed to equal 1.0 for welded-studs (since the effect of lower concrete
density is already taken into account in the calculation of nominal shear
capacity (f vs) using Equation 8.3.2.1(2)), and a constant value of 0.8 for
channels and high-strength structural bolts.
(b)
A procedure for calculating the nominal shear capacity (f vs) of channel or highstrength structural bolt shear connectors during the initial part of Construction
Stage 5 when 15 ≤ f′cj < 20 MPa, previously omitted from AS 2327.1, has been
included, viz. at f′cj = 15 MPa, f vs equals 80% of the values given in Table 8.2
and Table 8.3 f′ c = 20 MPa, and linear interpolation is used for values of f′ cj
between 15 and 20 MPa.
(c)
The Grade 300, 100 PFC (parallel flange channel) may now be used as a fully
equivalent shear connector to the Grade 250, 100 TFC (channel).
2
Open-rib and closed-rib profiles Distinction is made between open-rib and closedrib profile steel sheeting when designing the shear connection of the composite beam.
3
Welded stud locations Clause 8.4.2 clarifies that when automatically welded studs
are placed in the pans of sheeting ribs deemed to be perpendicular to the steel beam,
no more than two studs are permitted between adjacent sheeting ribs. New rules have
been written to allow shear connectors to be placed closer to steel ribs of closed-rib
profiles.
4
New reference material New reference material has been provided for designers
regarding the design of beams with large web penetrations and design for occupantinduced vibrations.
5
Reinforcement fyr = 500. The maximum design yield strength has been increased to
500 MPa for the longitudinal shear reinforcement in the composite slab.
The terms ‘normative’ and ‘informative’ are used in this Standard to define the application
of the appendix to which they apply. A ‘normative’ appendix is an integral part of a
Standard, whereas an ‘informative’ appendix is only for information and guidance.
3
AS 2327.1—2003
CONTENTS
Page
SECTION 1 SCOPE AND GENERAL
1.1 SCOPE......................................................................................................................... 6
1.2 GENERAL................................................................................................................... 6
1.3 REFERENCED DOCUMENTS................................................................................... 9
1.4 DEFINITIONS........................................................................................................... 10
1.5 EXISITING STRUCTURES...................................................................................... 16
1.6 DESIGN INFORMATION ........................................................................................ 16
1.7 CONSTRUCTION..................................................................................................... 17
1.8 NOTATION............................................................................................................... 17
SECTION 2 MATERIALS
2.1 STEEL ....................................................................................................................... 25
2.2 CONCRETE AND REINFORCEMENT ................................................................... 25
2.3 MECHANICAL PROPERTIES ................................................................................. 25
SECTION 3 GENERAL DESIGN REQUIREMENTS
3.1 DESIGN .................................................................................................................... 27
3.2 LOADS AND OTHER ACTIONS............................................................................. 28
3.3 DESIGN FOR LIMIT STATES ................................................................................. 28
SECTION 4 ACTIONS AND DESIGN SITUATIONS
4.1 GENERAL................................................................................................................. 30
4.2 CONSTRUCTION STAGES ..................................................................................... 30
SECTION 5 EFFECTIVE SECTION AND DESIGN ACTION EFFECTS FOR STRENGTH
DESIGN
5.1 GENERAL................................................................................................................. 32
5.2 EFFECTIVE SECTION OF A COMPOSITE BEAM CROSS-SECTION ................. 32
5.3 CALCULATION OF DESIGN ACTION EFFECTS DUE TO DESIGN LOADS ..... 37
SECTION 6 DESIGN FOR STRENGTH
6.1 GENERAL................................................................................................................. 39
6.2 DESIGN .................................................................................................................... 39
6.3 POTENTIALLY CRITICAL CROSS-SECTIONS .................................................... 41
6.4 CALCULATION OF DESIGN VERTICAL SHEAR CAPACITY (φVu) AND
DESIGN MOMENT CAPACITY (φMbv) AS A FUNCTION OF DEGREE OF
SHEAR CONNECTION (β) ...................................................................................... 42
6.5 CALCULATION OF MINIMUM DEGREE OF SHEAR CONNECTION β i AT
POTENTIALLY CRITICAL CROSS-SECTIONS .................................................... 42
6.6 DISTRIBUTION OF SHEAR CONNECTORS BETWEEN POTENTIALLY
CRITICAL CROSS-SECTIONS AND BEAM ENDS ............................................... 43
SECTION 7 DESIGN FOR SERVICEABILITY
7.1 GENERAL................................................................................................................. 45
7.2 DEFLECTION CONTROL........................................................................................ 45
7.3 CRACK CONTROL .................................................................................................. 47
7.4 VIBRATION CONTROL .......................................................................................... 47
AS 2327.1—2003
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Page
SECTION 8 DESIGN OF SHEAR CONNECTORS
8.1 GENERAL................................................................................................................. 48
8.2 SHEAR CONNECTORS ........................................................................................... 48
8.3 SHEAR CAPACITY OF SHEAR CONNECTORS ................................................... 50
8.4 DETAILING OF SHEAR CONNECTORS ............................................................... 52
SECTION 9 TRANSFER OF LONGITUDINAL SHEAR IN CONCRETE
9.1 GENERAL................................................................................................................. 60
9.2 DEFINITIONS........................................................................................................... 60
9.3 DESIGN .................................................................................................................... 60
9.4 LONGITUDINAL SHEAR SURFACES ................................................................... 61
9.5 DESIGN LONGITUDINAL SHEAR FORCE (V*L).................................................. 65
9.6 NOMINAL LONGITUDINAL SHEAR CAPACITY (VL)......................................... 66
9.7 TYPES 1, 2 AND 3 LONGITUDINAL SHEAR REINFORCEMENT ...................... 67
9.8 TYPE 4 LONGITUDINAL SHEAR REINFORCEMENT......................................... 67
SECTION 10 DESIGN FOR FIRE RESISTANCE
10.1 REQUIREMENTS..................................................................................................... 70
10.2 DEFINITIONS........................................................................................................... 70
10.3 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY....................... 71
10.4 DETERMINATION OF LIMITING TEMPERATURE OF THE STEEL.................. 71
10.5 DETERMINATION OF TIME AT WHICH LIMITING TEMPERATURE IS
ATTAINED FOR PROTECTED MEMBERS ........................................................... 71
10.6 DETERMINATION OF TIME AT WHICH LIMITING TEMPERATURE IS
ATTAINED FOR UNPROTECTED MEMBERS...................................................... 73
10.7 DETERMINATION OF PSA FROM A SINGLE TEST............................................ 74
10.8 THREE-SIDED FIRE EXPOSURE CONDITION..................................................... 74
10.9 CONNECTIONS AND WEB PENETRATIONS....................................................... 74
10.10 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY BY OTHER
CALCULATION METHODS ................................................................................... 75
SECTION 11 CONSTRUCTION
11.1 GENERAL................................................................................................................. 76
11.2 CONSTRUCTION SEQUENCE AND LOADS ........................................................ 76
11.3 STEELWORK ........................................................................................................... 76
11.4 FORMWORK AND FALSEWORK.......................................................................... 76
11.5 REINFORCEMENT .................................................................................................. 77
11.6 CONCRETE .............................................................................................................. 77
11.7 FIRE PROTECTION MATERIAL ............................................................................ 77
SECTION 12 LOAD TESTING
12.1 GENERAL................................................................................................................. 78
12.2 PROOF TESTING ..................................................................................................... 78
12.3 PROTOTYPE TESTING ........................................................................................... 79
12.4 TEST REPORTS ....................................................................................................... 80
5
AS 2327.1—2003
Page
APPENDICES
A
LIST OF REFERENCED DOCUMENTS.................................................................. 81
B
CALCULATION OF DEFLECTIONS BY SIMPLIFIED METHOD........................ 83
C
SUGGESTED LIMITS FOR CALCULATED DEFLECTIONS................................ 90
D
CALCULATION OF DESIGN MOMENT CAPACITY (φMbv) AS A
FUNCTION OF DEGREE OF SHEAR CONNECTION (β)............................................ 91
E
FLOW CHARTS ..................................................................................................... 107
F
CONSTRUCTION STAGES AND MINIMUM CONSTRUCTION LOADS.......... 114
G
DESIGN FOR FIRE RESISTANCE OF CONCRETE SLABS................................ 119
H
INFORMATION FOR DETERMINATION OF ACTION EFFECTS ..................... 120
I
BIBLIOGRAPHICAL REFERENCES .................................................................... 123
AS 2327.1—2003
6
STANDARDS AUSTRALIA
Australian Standard
Composite structures
Part 1: Simply supported beams
SECT ION
1
SCOPE
AND
GENERA L
1.1 SCOPE
This Standard sets out minimum requirements for the design, detailing and construction of
simply supported composite beams composed of a steel beam and a concrete slab
interconnected with shear connectors, including applications where the slab incorporates
profiled steel sheeting, as defined in Clause 1.2.
This Standard does not cover the design of composite beams—
(a)
where the elements of the steel beam are less than 3 mm thick or the value of the
yield stress (f yb ) assumed in design exceeds 450 MPa (see Note 1);
(b)
where the strength grade of the slab concrete exceeds 40 MPa;
(c)
where the slab is precast or prestressed;
(d)
with negative design moments (see Note 2);
(e)
subjected to dynamic loads;
(f)
for road or railway bridges (see Note 3); or
(g)
for fatigue.
NOTE:
1
This does not preclude the use of steels with a minimum yield strength greater than 450 MPa.
2
For the design of composite beams with negative design moments reference may be made to
BS 5950:3:1990, Code of Practice for Design of Simple and Continuous Composite Beams.
3
For the design of composite bridge beams, reference should be made to HB 77 the AUSTROADS
Bridge Design Code.
1.2 GENERAL
1.2.1 Components
This Standard applies only to composite beams for which the components satisfy the
requirements specified in Clauses 1.2.2 to 1.2.5.
1.2.2 Steel beam
The steel beam shall be entirely below, but in contact with, the soffit of the concrete slab,
and shall be of structural steel, symmetrical about its vertical axis (i.e., doubly symmetric
or monosymmetric), suitably proportioned (see Note) and have one of the following forms
(see Figure 1.2.2)—
(a)
a hot-rolled I-section, or channel section;
(b)
a welded I-section;
(c)
a rectangular cold-formed hollow section;
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AS 2327.1—2003
(d)
a fabricated I-section, Tee section, channel section or rectangular hollow section; or
(e)
any of the above sections as appropriate with an additional plate welded to the bottom
flange.
NOTE: Steel beams with a slender section (i.e., λ e > λ ey for any top flange or web plate
element either partially or fully in compression (see Clause 5.2.3.3)) are not permitted.
When a fire resistance level (FRL) must be achieved, a fire protection material may be used
to protect the exposed surfaces of the steel beam.
FIGURE 1.2.2 ALTERNATIVE STEEL BEAM TYPES
1.2.3 Concrete slab
The concrete slab shall be of reinforcement in accordance with AS/NZS 4671, nonprestressed concrete complying with AS 3600, and be either a solid slab (without a haunch)
or a composite slab (see Figure 1.2.3).
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FIGURE 1.2.3 ALTERNATIVE CONCRETE SLAB TYPES
1.2.4 Profiled steel sheeting
The geometry of the profiled steel sheeting incorporated in a composite slab shall satisfy all
of the following requirements (see Figure 1.2.4(a)):
(a)
The overall height of a steel rib (h r) shall be not greater than 80 mm, excluding any
embossments.
(b)
The width of the opening at the base of a steel rib (b b) shall be not greater than
20 mm.
(c)
The area of the voids formed by the steel ribs in the concrete shall be not greater than
20% of the area of the concrete within the depth of the steel ribs.
(d)
The width of the concrete between the mid-height of adjacent steel ribs (b cr) shall be
not less than 150 mm.
(e)
The cover slab thickness (that is, the thickness of the concrete above the steel ribs,
which equals D c − h r) shall be not less than 65 mm.
Longitudinal stiffeners in the pans of the sheeting with an overall height (h s) greater than
10 mm, measured from the same face of the sheet (see Figure 1.2.4(b)), shall be deemed to
be steel ribs for the purpose of this Standard.
Open-rib and closed-rib profiles shall be defined as follows:
(i)
Closed-rib profiles All of the steel ribs of a closed-rib profile shall satisfy the
geometric requirements shown in Figure 1.2.4 (c).
(ii)
Open-rib profiles A profile that is not a closed-rib profile shall be treated as an
open-rib profile.
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AS 2327.1—2003
NOTE: Dimensions are to be taken between adjacent sheeting surfaces
(c) Closed-rib profile
FIGURE 1.2.4 PROFILED STEEL SHEETING GEOMETRY
1.2.5 Shear connectors
The shear connectors attached to the top flange of the steel beam shall be any one of the
following three types (see Figure 1.2.5):
(a)
Headed studs.
(b)
Channels.
(c)
High-strength structural bolts.
1.3 REFERENCED DOCUMENTS
The documents referred to in this Standard are listed in Appendix A.
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FIGURE 1.2.5 ACCEPTABLE SHEAR CONNECTOR TYPES
1.4 DEFINITIONS
1.4.1 General
For the purpose of this Standard, the definitions below apply. Definitions applying only to a
particular clause or section are given in that clause or section and referred to below.
1.4.2 Administrative definitions
1.4.2.1 Authority
A body having regulatory powers, in the area in which the structure is to be erected, to
control the design and erection of the structure.
1.4.2.2 Drawings
The drawings forming part of the project documents setting out the work to be executed.
1.4.2.3 May
Indicates the existence of an option.
1.4.2.4 Principal
The purchaser or owner of the structure being constructed or his nominated representative.
1.4.2.5 Shall
Indicates that a statement is mandatory.
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AS 2327.1—2003
1.4.2.6 Should
Indicates a recommendation.
1.4.2.7 Specification
The specification forming part of the project documents setting out the work to be executed.
1.4.3 Technical definitions
1.4.3.1 Action
The cause of stress, deformation or displacement in a structure, or in a component member
of the structure.
1.4.3.2 Action effect
The force, moment, deformation, or like effect, produced in the members of a structure
(or its foundations) by an action or combination of actions.
1.4.3.3 Capacity factor
A factor by which the nominal capacity or strength is multiplied to obtain the design
capacity or strength.
1.4.3.4 Characteristic strength
The value of a material strength, as assessed by a standard test, which has a 95% probability
of being exceeded in all such tests on the same material.
1.4.3.5 Closed-rib profile
A profiled steel sheeting where the geometry of all of the steel ribs satisfies the geometric
requirements of Figure 1.2.4 (c).
1.4.3.6 Complete shear connection (β = 1)
The condition where the moment capacity of the cross-section of the composite beam is not
governed by the strength of the shear connection.
1.4.3.7 Composite action
Interaction between the steel beam and the concrete slab to resist action effects as a single
structural member; assumed to commence when the concrete in the slab has attained a
compressive strength of at least 15 MPa (i.e., at the start of Construction Stage 5). It is
assumed to be fully developed once the compressive strength of the concrete (estimated by
f′ cj (see Clause 4.2.2)) is equal to or greater than its specified design value f′c (i.e., at or
after the start of Construction Stage 6).
1.4.3.8 Composite beam
A steel beam and a solid or composite slab, interconnected by shear connection to act
together to resist action effects as a single structural member.
1.4.3.9 Composite slab
A cast in situ concrete slab that incorporates profiled steel sheeting as permanent soffit
formwork.
1.4.3.10 Concrete
A mixture of cement, aggregates and water, with or without the addition of chemical
admixtures, which conforms to both AS 1379 and AS 3600.
1.4.3.11 Concrete slab
A slab cast monolithically with in situ concrete and reinforcement, with or without profiled
steel sheeting.
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1.4.3.12 Connector group
(See Clause 9.2).
1.4.3.13 Connector set
(See Clause 9.2).
1.4.3.14 Construction stage
One of the periods defined in Clause 4.2.
1.4.3.15 Cover
The least distance between the surface of reinforcement or shear connectors and the nearest
permanent surface of the concrete, excluding any applied surface finish.
1.4.3.16 Cover slab
Concrete above the steel ribs in a composite slab.
1.4.3.17 Critical cross-section
A transverse cross-section at which the ratio of either the design bending moment (M*) to
the design moment capacity ( φM bv), or the design vertical shear force (V*) to the design
vertical shear capacity (φV u ) is a maximum.
1.4.3.18 Degree of shear connection (β )
The value obtained when the compressive force in the concrete at the strength limit state
(Fcp) is divided by the compressive force in the concrete corresponding to complete shear
connection in the absence of vertical shear force (Ecc) (see Figure 6.1).
1.4.3.19 Design action effect
The action effect computed from the design action (load).
1.4.3.20 Design capacity
The product of the nominal capacity and the capacity factor.
1.4.3.21 Design life
The period over which a structure or structural element is required to perform its intended
function without undue maintenance.
1.4.3.22 Design load
The combination of loads and load factors as specified in AS/NZS 1170.0.
1.4.3.23 Effective section
The portion of a composite beam cross-section considered effective in resisting action
effects in bending (see Clause 5.2).
1.4.3.24 Effective span
See Clause 5.3.2.
1.4.3.25 Effective width of concrete flange
The overall width of the portion of a concrete slab, at a composite beam cross-section,
considered effective in resisting compression after allowing for shear lag.
1.4.3.26 Effective width of steel flange
The overall width of the portion of a flange of a steel beam, at a composite beam crosssection, considered effective in resisting compression after allowing for flange buckling.
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AS 2327.1—2003
1.4.3.27 Exposed surface area to mass ratio
See Clause 10.2.
1.4.3.28 Fire exposure condition
See Clause 10.2.
1.4.3.29 Fire protection system
See Clause 10.2.
1.4.3.30 Fire-resistance level (FRL)
See Clause 10.2.
1.4.3.31 Fire-resistance period
See Clause 10.2.
1.4.3.32 Full interaction
The condition of a composite beam assuming no slip occurs along the length of the beam at
the concrete/steel interface.
1.4.3.33 In-service condition
Period after completion of construction when the structure is serving its intended function.
1.4.3.34 Insulation
See Clause 10.2.
1.4.3.35 Integrity
See Clause 10.2.
1.4.3.36 Lightweight concrete
Concrete, as previously defined, having a saturated surface-dry density in the range
1800 kg/m 3 to 2100 kg/m 3 .
1.4.3.37 Limit state
Any limiting condition or criterion beyond which a structure, or a member, fails to fulfil its
intended function.
1.4.3.38 Load
An externally applied force.
1.4.3.39 Longitudinal shear plane
See Clause 9.2.
1.4.3.40 Longitudinal shear reinforcement
See Clause 9.2.
1.4.3.41 Longitudinal shear surface
See Clause 9.2.
1.4.3.42 Nominal capacity
The capacity of a member or component calculated, without the capacity factor, in
accordance with this Standard.
1.4.3.43 Nominal load
A load as specified in Clause 4.1.1.
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1.4.3.44 Normal-weight concrete
Concrete, as previously defined, having a saturated surface-dry density greater than
2100 kg/m 3 and less than or equal to 2800 kg/m 3 .
1.4.3.45 One-way action
Flexural action significant in one direction only.
1.4.3.46 One-way slab
A solid or composite slab characterized by one-way action.
1.4.3.47 Open-rib profile
A profiled steel sheeting with open and possibly closed steel ribs.
1.4.3.48 Partial shear connection (β < 1.0)
The condition for which the moment capacity of the cross-section of the composite beam is
governed by the strength of the shear connection.
1.4.3.49 Period of structural adequacy (PSA) (fire)
See Clause 10.2.
1.4.3.50 Ponding
Appreciably non-uniform depth of slab as a result of the steel beam or formwork deflecting
under the weight of the plastic concrete and slab reinforcement.
1.4.3.51 Potentially critical cross-section
A transverse cross-section that is likely to be critical (see Clause 6.3).
1.4.3.52 Precast slab
Slab incorporating precast concrete units with or without cast in situ concrete.
1.4.3.53 Prestressed slab
Slab incorporating prestressed tendons.
1.4.3.54 Profiled steel sheeting
Steel sheeting cold-formed into a profile used as permanent formwork for the soffit of
composite slabs.
1.4.3.55 Proof testing
The application of specified test loads to a member or assemblage of members, to
demonstrate adequate structural performance of only that member or assemblage.
1.4.3.56 Prop
A temporary support fitted beneath a steel beam or formwork to support loads during
construction.
1.4.3.57 Prototype (fire)
See Clause 10.2.
1.4.3.58 Prototype testing
The application of limit-state test actions to two or more prototype members or
assemblages, which are representative of a group of members or assemblages nominally
identical with those tested, for the purpose of demonstrating conformance of the group with
specified limit-state criteria.
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1.4.3.59 Reinforcement, reinforcing steel
Steel bar, wire, or fabric (but not tendons or fibres) placed in a concrete slab.
1.4.3.60 Serviceability limit state
The loss of fitness for intended use under specified in-service conditions.
1.4.3.61 Shear connection
The interconnection between the steel beam and concrete slab of a composite beam, which
enables the two components to act together as a single structural member, comprising the
shear connectors, slab concrete and longitudinal shear reinforcement.
1.4.3.62 Shear connector
A mechanical device attached to the top flange of a steel beam which forms part of the
shear connection.
1.4.3.63 Shear ratio (γ )
The ratio at a cross-section of the design vertical shear force (V*) to the design vertical
shear capacity (φV u ).
1.4.3.64 Simply supported beam
A beam assumed to act as a single-span member without negative design moments.
1.4.3.65 Solid slab
A concrete slab with a flat soffit and without a haunch, cast in situ on removable formwork
and reinforced in accordance with AS 3600.
1.4.3.66 Standard fire test
See Clause 10.2.
1.4.3.67 Stickability (fire)
See Clause 10.2.
1.4.3.68 Strength limit state
Collapse, or loss of structural integrity, under specified extreme-load conditions.
1.4.3.69 Structural adequacy (fire)
See Clause 10.2.
1.4.3.70 Tensile strength
The maximum strength in tension specified for the relevant grade and type of steel in the
appropriate Australian Standard.
1.4.3.71 Tributary area
See Clause 5.3.2.
1.4.3.72 Two-way action
Flexural action significant in two directions, usually at right angles to one another.
1.4.3.73 Two-way slab
A solid slab characterized by two-way action.
1.4.3.74 Yield strength (or stress)
The minimum yield stress in tension specified for the grade and type of steel in the
appropriate Australian Standard.
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AS 2327.1—2003
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1.5 EXISITING STRUCTURES
When the strength or serviceability of an existing structure is to be evaluated, the general
principles of this Standard may be applied using the actual properties of the materials in the
structure. The evaluation may include the proof testing of beams in accordance with
Clause 12.2.
1.6 DESIGN INFORMATION
1.6.1 Design data
The following design details shall be shown on the drawings:
(a)
The reference number and date of issue of applicable and current design Standards
and, if applicable, any amendments to them.
(b)
The nominal design live loads during construction and in-service, as appropriate.
(c)
The durability exposure classification for the concrete and, if applicable, the
corrosion protection for the exposed steelwork and profiled steel sheeting.
(d)
The required fire-resistance level, if applicable.
(e)
The grades and types of reinforcement.
(f)
The grades of steel in the steel beams.
(g)
The types and, if applicable, grades of shear connectors and their method of
attachment.
(h)
The type, class and strength designation of the concrete.
1.6.2 Design details
The project drawings or the specification, or both, shall include the following design details
as appropriate:
(a)
The dimensions and, if applicable, camber and designation of each steel member.
(b)
The support or connection details for the steel beams including location, size, grade
and category of bolts or welds, as applicable.
(c)
Details of the type, size, location and spacing of shear connectors, particularly in
relation to the position of profiled steel sheeting ribs.
(d)
The overall thickness of the slab inclusive of profiled steel sheeting, if applicable,
and the size and location of any openings, rebates, major voids or conduits in the slab.
(e)
The grade, size, quantity and location of all reinforcement, and other structural
embedments, as appropriate.
(f)
The finish and method of control for unformed concrete surfaces.
(g)
In the case of solid slabs, the class of formwork for the surface finish specified in
accordance with AS 3610.
(h)
In the case of composite slabs, the proprietary name, base metal thickness, coating
class and similar relevant data for the profiled steel sheeting, or appropriate selection
or performance criteria.
(i)
The concrete curing procedure.
(j)
The location and details of any movement joints or planned construction joints in the
concrete slabs.
(k)
The minimum period of time before stripping of forms or removal of props, as
appropriate.
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AS 2327.1—2003
17
(l)
The values of the nominal live loads used in design.
(m)
The assumed construction sequence.
(n)
The climatic or other local conditions relevant to the durability design of the
structure.
(o)
The design life of the structure (if applicable).
(p)
Any other constraint on construction assumed in the design.
(q)
Fire-resistance requirements and fire-protection details, if applicable.
(r)
Any other requirements.
1.7 CONSTRUCTION
Composite beams designed in accordance with this Standard shall be constructed so that all
the requirements of the design, as contained in the project drawings and specification, are
satisfied.
1.8 NOTATION
The symbols used in this Standard are listed below. Symbols that occur in more than one
clause are defined below and used in the various clauses without further reference. Symbols
which occur only in one clause are defined in that clause as well as being listed below.
Unless otherwise specified, the following rules apply:
(a)
Where non-dimensional ratios are involved, both the numerator and denominator are
expressed in identical units.
(b)
The dimensional units for length, force and stress in all expressions or equations are
to be taken as millimetres (mm), newtons (N) and megapascals (MPa) respectively.
(c)
The units of fractional powers of stress (e.g.
(d)
An asterisk superscript placed after a symbol (e.g. M*) denotes a design action effect
resulting from the design load for the strength limit state.
f c′ ) are to be taken as those for stress.
A
=
tributary area associated with a steel or composite beam for the
calculation of nominal live load
Af
=
cross-sectional area of a flange of the steel beam
A f1 , A f2
=
values of A f for top and bottom flanges, respectively
As
=
cross-sectional area of the steel beam
A sc
=
cross-sectional area of the shank of a headed stud, or the minor
diameter area of a high-strength structural bolt as defined in
AS 1275
A sp.b
=
cross-sectional area of bottom-face reinforcement crossing a
longitudinal shear plane through the concrete flange (see
Figure 9.4.1(a))
A sp.t
=
cross-sectional area of top-face reinforcement crossing a
longitudinal shear plane through the concrete flange (see
Figure 9.4.1(a))
A sv
=
cross-sectional area of reinforcement crossing a longitudinal shear
surface through the concrete flange
A sv.min
=
the minimum cross-sectional area required of reinforcement
crossing a longitudinal shear surface through the concrete flange
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AS 2327.1—2003
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A sv.1 , A sv.2 , A sv.3
=
values of Asv corresponding to shear surface types 1, 2 and 3,
respectively
Aw
=
cross-sectional area of the web(s) of the steel beam
b
=
clear width of plate element outstand
b 1, b 2
=
centre-to-centre spacing of adjacent beams or distance from centre
of steel beam to edge of slab outstand (see Figure 5.2.2.1)
bb
=
width of opening at base of steel rib in a composite slab (see
Figure 1.2.4(a))
b cf
=
effective width of the concrete slab compression flange (see
Figure 5.2.2.1)
b cr
=
width of the concrete rib in a composite slab at mid-height of the
steel ribs
=
s r – bsr
b e1 , be2
=
concrete slab effective width outstands on opposite sides of steel
beam centre-line (see Figures 5.2.2.1 and 9.5)
bf
=
width of a steel beam flange
bs
=
support width
b sf1
=
effective width of steel beam top flange
b sf2
=
overall width of steel beam bottom flange
b sr
=
width of steel rib in a composite slab at its mid-height (see
Figure 1.2.4(a))
bx
=
overall width of shear connectors at a beam cross-section (see
Figure 9.4.1)
b y1 , b y2
=
segment lengths of shear surface perimeter (see Figure 9.4.2.5)
c 1, c2
=
constants (see Paragraph B3.2, Appendix B)
Db
=
overall depth of a composite beam
Dc
=
overall depth of a concrete slab including the thickness of any
profiled steel sheeting if present
Ds
=
overall depth of a steel beam
d1
=
clear depth between flanges of a steel beam ignoring fillets or welds
db
=
nominal diameter of a reinforcing bar (see Clause 9.7.3)
d bs
=
nominal shank diameter of a headed-stud or a high-strength
structural bolt shear connector
dc
=
depth of the assumed uniform compressive stress block in the
concrete slab at the strength limit state
dh
=
calculated depth of the compressive zone below the top of the
concrete slab at the strength limit state
d sg
=
distance from the top of the concrete slab to the centroid of the steel
beam
d sr
=
distance from the top of the concrete slab to the line of action of
either Fst or Fstf
Ec
=
elastic modulus of the slab concrete
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AS 2327.1—2003
19
E cT
=
elastic modulus of the slab concrete at T°C > 20°C
Es
=
elastic modulus of steel at 20°C (= 2 × 105 MPa)
E sT
=
elastic modulus of steel at T°C > 20°C
Fb
=
balancing compressive force in steel beam [either (F sc − 2Fscf ) or
(Fsc − 2Fscf − 2Fscw)]
Fc
=
compressive force in the concrete slab at a cross-section at the
strength limit state
=
F cc or Fcp as appropriate
F c1
=
longitudinal compressive capacity of concrete cover slab within slab
effective width
F c2
=
longitudinal compressive capacity of concrete between steel
sheeting ribs within slab effective width
F cc
=
compressive force in concrete slab at a cross-section with complete
shear connection where γ ≤ 0.5 at the strength limit state
F cc.i
=
value of Fcc corresponding to potentially critical cross-section (i)
F ccf
=
compressive force in concrete slab at a cross-section with complete
shear connection where γ = 1.0 at the strength limit state
F cp
=
compressive force in concrete slab at a cross-section with partial
shear connection where γ ≤ 0.5 at the strength limit state
F cp.i
=
value of Fcp corresponding to potentially critical cross-section (i)
F cpf
=
compressive force in concrete slab at a cross-section with partial
shear connection where γ = 1.0 at the strength limit state
Fs
=
resultant tensile force in steel beam at the strength limit state
F sc
=
balancing compressive force in steel beam [either (F st − 2Fcp) or
(Fstf − Fccf )]
F scf
=
compressive capacity of steel beam top flange, assuming entire
effective flange area is at yield stress f yf
F scw
=
compressive capacity of steel beam web(s), assuming entire
effective portion is at yield stress f yw
F st
=
tensile capacity of steel beam, assuming that the entire crosssectional area has yielded in tension
F stf
=
tensile capacity of the steel beam ignoring web(s), assuming that the
entire cross-sectional area of the flanges has yielded in tension
f′ c
=
28 day characteristic compressive cylinder strength of concrete
f′ cj
=
estimated characteristic compressive strength of concrete at j days
(see Clause 4.2.2) but taken as not greater than f ′c
fcmj
=
average compressive strength of sample cylinders after j days of site
curing (see Clause 4.2.2)
f ds
=
design shear capacity of a shear connector (see Clause 8.3.4)
f max
=
maximum stress in steel beam (see Paragraph B4)
f uc
=
tensile strength of the shear-connector material used in design
f vs
=
nominal shear capacity of a shear connector (see Clause 8.3.2)
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AS 2327.1—2003
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fy
=
yield strength of steel used in design
f yb
=
yield strength of steel beam used in design
f yf , f yw
=
yield strength of the flange and web, respectively, of the steel beam
f yr
=
yield strength of the steel reinforcement used in design
f yT
=
yield strength of steel beam at T°C
G
=
total dead load
G sup
=
superimposed dead load
G C1.3
=
permanent dead load which arises during Construction Stages 1 to 3
hc
=
overall height of a shear connector (see Clause 9.4.2.4)
he
=
effective thickness of concrete slab
hi
=
thickness of fire protection material
hr
=
height of the steel ribs in profiled steel sheeting
hs
=
height of longitudinal stiffener in profiled steel sheeting (see
Figure 1.2.4(b))
Iet
=
effective second moment of area of a composite cross-section
Ieti
=
value of I et under immediate loads
I et l
=
value of I et under long-term loads
Is
=
second moment of area of the steel beam about its centroid of area
It
=
second moment of area of transformed section with respect to steel
I ti
=
transformed second moment of area of a composite beam
cross-section under immediate loads, taken about the centroid of the
transformed area
Itl
=
transformed second moment of area of a composite beam
cross-section under long-term loads, taken about the centroid of the
transformed area
k
=
elastic neutral axis parameter
k 0 to k 6
=
regression coefficients (see Section 10)
kn
=
a load-sharing factor (see Clause 8.3.4)
ksm
=
exposed surface area to mass ratio
ksm1
=
exposed surface area to mass ratio above a penetration
ksm2
=
exposed surface area to mass ratio below a penetration
L
=
distance between the centre-lines of adjacent members supporting a
composite beam; or
=
distance available for reinforcement anchorage (see Clause 9.7.3)
=
effective span of a composite beam (see Clause 5.3.3); or
=
effective span of profiled steel sheeting (see Paragraph C2,
Appendix C)
=
clear distance between the flanges of adjacent steel beams spanning
in the same direction
L ef
Ln
 Standards Australia
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AS 2327.1—2003
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L sy.t
=
development length for reinforcement in tension (see Clause 9.7.3)
Lw
=
greatest internal dimension of holes drilled or cut in steel beam web
l
=
length of channel shear connector (see Figure 8.2)
M*
=
design bending moment at a cross-section
Mb
=
nominal moment capacity of a composite cross-section where
γ ≤ 0.5 and 0 < β < 1.0
M b.5
=
value of M b corresponding to β = 0.5
M b.ψ
=
value of M b corresponding to β = ψ
M bc
=
nominal moment capacity of a composite beam cross-section where
γ ≤ 0.5 and β = 1.0
M bf
=
nominal moment capacity of a composite beam cross-section where
γ = 1.0 and 0 < β < ψ, neglecting any contribution of the steel beam
web(s)
M bfc
=
nominal moment capacity of a composite beam cross-section where
γ = 1.0 and β = 1.0, neglecting any contribution of the steel beam
web(s)
M bv
=
nominal moment capacity of a composite beam cross-section where
0 ≤ γ ≤ 1.0 and 0 ≤ β ≤ 1.0
M bv.0
=
value of M bv corresponding to β = 0
M bv.ψ
=
value of M bv corresponding to β = ψ
M bvc
=
nominal moment capacity of a composite beam cross-section where
0 ≤ γ ≤ 1.0 and β = 1.0
Ms
=
nominal moment capacity of steel beam section
Msf
=
nominal moment capacity of steel beam section neglecting any
contribution of the web(s)
n
=
total number of shear connectors provided between a cross-section
and an end of the composite beam
nA
=
number of shear connectors between a potentially critical crosssection (i) and end A of a beam (see Figure 6.1)
nB
=
number of shear connectors between a potentially critical crosssection (i) and end B of a beam (see Figure 6.1)
ni
=
minimum number of shear connectors (with the same design shear
capacity fds) between a potentially critical cross-section i and the
ends of the beam to satisfy the design requirement φM bv ≥ M*
n′ i
=
number of shear connectors provided which are considered fully
effective in contributing to the design moment capacity (φM bv) of a
potentially critical cross-section (i)
n ic
=
minimum number of shear connectors (with the same design shear
capacity fds) required between a potentially critical cross-section (i)
and the ends of the beam to achieve complete shear connection
n i.min
=
the lesser number of shear connectors provided between a
composite beam cross-section and the ends of the beam
nx
=
number of shear connectors in a group at a transverse cross-section
of a composite beam
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AS 2327.1—2003
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Q
=
live load
Ru
=
nominal capacity of a composite member, or a component of the
member, to resist action effects at the strength limit state
Rs
=
nominal capacity of a composite member, or a component of the
member, to resist action effects at the serviceability limit state
re
=
elastic neutral axis parameter measured from below the steel beam
top flange (see Table 5.1)
rf
=
maximum value along the length of the beam of the ratio of the
design bending moment (M*) under design load for fire to the
design moment capacity (φM bv) at room temperature
rp
=
plastic neutral axis parameter (see Table 5.1)
rl
=
the corner outside radius of a rectangular hollow section (see
Figure 8.4.3.1)
S*
=
design action effects in general
s
=
standard deviation
sc
=
longitudinal spacing of shear connectors between adjacent groups
sr
=
transverse spacing of steel ribs in a profiled steel sheet (see
Figure 1.2.4(a))
T
=
steel temperature in degrees Celsius
Tl
=
limiting steel temperature in degrees Celsius
t
=
plate element thickness; or
=
time
tf
=
thickness of the flange of a steel beam
t f1 , t f2
=
values of t f corresponding to the top and bottom flanges,
respectively
tw
=
thickness of the web(s) of a steel beam
t′ w
=
effective thickness of non-compact web(s) of a steel beam (see
Figure 5.2.3.3(b))
u
=
perimeter length of a shear surface
u 1, u 2, u 3
=
values of u corresponding to Type 1, 2 and 3 shear surfaces (see
Figure 9.4.2.5)
V*
=
design vertical shear force acting at a composite beam cross-section
V* L
=
design longitudinal shear force per unit length acting on a
longitudinal cross-section of a concrete slab flange
V* L.tot
=
total design longitudinal shear force per unit length of beam
VL
=
nominal longitudinal shear capacity per unit length of the concrete
slab at the strength limit state
Vu
=
nominal vertical shear capacity of a composite beam cross-section
at the strength limit state
 Standards Australia
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AS 2327.1—2003
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x
=
distance from outside edge of effective width to centre of
longitudinal shear surface (see Clause 9.5); or
=
depth of non-compact portion of web to be ignored in design (see
Figure 5.2.3.3(a))
Z cb
=
section modulus of the composite beam corresponding to the
extreme bottom fibres of the steel beam
Z ct
=
section modulus of the composite beam corresponding to the
extreme top fibres of the steel beam
Z sb
=
section modulus of the steel beam corresponding to the extreme
bottom fibres of the steel beam
Z st
=
section modulus of the steel beam corresponding to the extreme top
fibres of the steel beam
α
=
modular ratio Es/Ec or EsT/E cT
β
=
degree of shear connection at a cross-section
=
F cp/Fcc (see Figure 6.1)
βi
=
minimum degree of shear connection at a potentially critical crosssection i to satisfy the design requirement φM bv ≥ M*
βm
=
degree of shear connection at the maximum moment cross-section
of a composite beam
γ
=
shear ratio at a composite beam cross-section
=
V*/( φV u ) ≤ 1.0
∆
=
maximum deflection of a composite beam under serviceability loads
δC1.3
=
immediate deflection of steel beam during Construction
Stages 1 to 3
δC5.6
=
immediate deflection of composite beam during Construction
Stages 5 to 6
δIi
=
immediate deflection of composite beam during in-service condition
δIl
=
long-term creep deflection of composite beam during in-service
condition
δIsh
=
long-term shrinkage deflection of composite beam during in-service
condition
δ inc
=
incremental deflection (see Paragraph B1)
δtot
=
total deflection (see Paragraph B1)
ε
=
yield stress factor (see Figure 5.2.3.3(a))
θ
=
acute angle between the steel ribs of a composite slab and the
longitudinal axis of the steel beam
λ
=
factor accounting for the inclination of profiled steel sheeting ribs
with respect to longitudinal axis of steel beam (see
Figure 5.2.2.2(b))
λe
=
plate element slenderness (see Clause 5.2.3.3)
λep
=
plate element plasticity slenderness limit
λey
=
plate element yield slenderness limit
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AS 2327.1—2003
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ρc
=
density of concrete
φ
=
capacity factor relevant to a strength limit state (see Clause 3.3.1)
ψ
=
value of β corresponding to complete shear connection of a
composite beam ignoring the presence of the steel beam web(s)
=
F ccf /Fcc (see Paragraph D3.3, Appendix D)
ψl
=
long-term live load factor used in assessing the design load for the
serviceability limit state
ψs
=
short-term live load factor used in assessing the design load for the
serviceability limit state
 Standards Australia
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AS 2327.1—2003
25
SECT ION
2
MATER I A L S
2.1 STEEL
2.1.1 Structural steel
Structural steel used in the steel beam component of the composite beam shall comply with
AS 1163, AS/NZS 1594, AS 3678, AS 3679.1 or AS 3679.2, as appropriate. Cold-formed
rectangular hollow steel sections manufactured in accordance with AS 1163 shall be grades
C350, C350L0, C450 or C450L0.
2.1.2 Bolts, nuts and washers
Bolts, nuts and washers used for fabricating and erecting the steel beam shall comply with
AS 1110, AS 1111, AS 1112 or AS/NZS 1252, as appropriate.
2.1.3 Welds and welding
Welding consumables, deposited weld metal and welding used to fabricate the steel beam or
attach channel shear connectors to the top flange shall comply with AS 1554.1, and welding
of headed-stud shear connectors shall comply with AS 1554.2.
2.1.4 Shear connectors
Shear connectors shall comply with AS 1554.2, AS/NZS 1252 or AS 3679.1, as appropriate.
Alternatively, shear connectors not complying with the above may be used, provided that—
(a)
their mechanical and other physical properties are not inferior; and
(b)
they comply with the other relevant requirements of this Standard.
2.1.5 Profiled steel sheeting
The steel strip used to produce the profiled steel sheeting shall comply with AS/NZS 1365
and AS 1397. As an additional requirement, the amount of oil residue on the surface of
profiled steel sheeting after manufacture shall not exceed 200 mg/m2 .
2.2 CONCRETE AND REINFORCEMENT
2.2.1 Concrete
The ingredients for, and the manufacture of, fresh (plastic) concrete used for the in situ
concrete slab of a composite beam, shall comply with AS 1379. The resulting hardened
concrete shall comply with AS 3600.
2.2.2 Reinforcement
Reinforcement used in the concrete slab of a composite beam shall comply with
AS/NZS 4671.
2.3 MECHANICAL PROPERTIES
The mechanical properties used for calculating the nominal (unfactored) strengths of the
component parts of the composite beam shall be determined in accordance with the
following:
(a)
Steel sections AS 4100, Section 2.
(b)
Bolts and nuts AS 1111 and AS 1112.
(c)
Welds AS 1554.1 and AS 1554.4.
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AS 2327.1—2003
(d)
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Shear connectors of the following types (see also Clause 8.2.1):
(i)
Channels AS/NZS 3679.1.
(ii)
Headed studs AS 1554.2.
(iii) High-strength structural bolts (Grade 8.8) AS/NZS 1252.
(e)
Concrete and reinforcement AS 3600 and AS/NZS 4671.
(f)
Galvanized steel strip for profiled steel sheeting AS 1397.
 Standards Australia
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27
AS 2327.1—2003
SECT ION 3
GENERA L DES IG N
REQU IREME NTS
3.1 DESIGN
3.1.1 Aim
The aim of structural design in accordance with this Standard is to provide a composite
beam that has adequate strength, is serviceable, stable, durable and fire-resistant (if
required), and satisfies other objectives such as economy and ease of construction.
A structural member has adequate strength and is serviceable if the probabilities of
structural failure and of loss of serviceability throughout its intended life are acceptably
low.
A structural member is stable overall if it does not overturn, tilt or slide throughout its
intended life.
A structural member is durable if it withstands the expected wear and deterioration
throughout its intended life without the need for undue maintenance or repair.
3.1.2 Requirements
The design of a composite beam and its components shall take into account, as appropriate,
the limit states of stability, strength, serviceability, fire resistance and any other relevant
design criteria, in accordance with the procedures specified in this Section.
Prior to the commencement of composite action, the design of the composite beam
components shall be in accordance with Clause 3.1.3.
NOTES:
1
A flowchart showing the sequence of the overall design process with respect to the various
limit states and construction stages is given in Appendix E.
2
Relevant construction stages are described in Appendix F.
3.1.3 Design of composite beam components
3.1.3.1 Steel beam
Prior to the development of composite action (i.e., Construction Stages 1 to 4), the steel
beam shall be designed in accordance with AS 4100 for the loads and other actions
specified in Clause 3.2. During construction and the in-service condition, end supports and
connections of the steel beam shall satisfy the relevant requirements of AS 4100.
NOTE: Where the formwork consists of profiled steel sheeting, the degree of lateral restraint
provided to the steel beam by the sheeting will depend on, amongst other things, the flexural
stiffness of the sheeting, the orientation of the sheeting ribs and the strength of the connection
between the sheeting and the beam.
3.1.3.2 Concrete slab
The concrete slab may be either a solid slab, or a composite slab (see Clause 1.2.3). The
slab shall be designed in accordance with AS 3600 if it is either a solid slab, or a composite
slab but no composite action between the concrete and the profiled steel sheeting is
considered. When composite action between the concrete and the profiled steel sheeting is
taken into account in design, appropriate design information shall be used.
NOTE: Design provisions for composite slabs are currently being prepared. In the interim, the
proprietary literature of profiled steel sheeting manufactures may be used, provided it is
supported by adequate test data.
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AS 2327.1—2003
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3.1.3.3 Profiled steel sheeting
Prior to the development of composite action (i.e., Construction Stages 1 to 4), the profiled
steel sheeting in a composite slab shall be designed in accordance with an appropriate
method for the loads and other actions defined in Clause 3.2. The calculated deflections
under these conditions shall not exceed the limits specified in Clause 7.2.
NOTE: In the absence of an appropriate Australian Standard, methods given in the proprietary
literature of the profiled steel sheeting manufacturer may be used, provided that they are
supported by adequate test data.
3.1.4 Composite beam minimum slab outstand
The outstand of a concrete slab (either solid or composite), which forms the flange of a
composite edge beam, shall be at least 150 mm wide measured from the vertical outside
edge of the slab to the edge of the nearest shear connector (see Figure 3.1.4).
FIGURE 3.1.4 COMPOSITE BEAM MINIMUM SLAB OUTSTAND
3.2 LOADS AND OTHER ACTIONS
3.2.1 Loads
The design of a composite beam for strength, serviceability, stability and fire resistance
shall take account of the action effects arising directly from the nominal loads specified in
Clause 4.1.1.
3.2.2 Other actions
Any other actions which significantly affect the strength, serviceability, stability or fire
resistance of the composite beam including but not limited to those actions specified in
Clause 4.1.2, shall be taken into account when determining the design loads.
3.2.3 Design loads
The design loads for the limit states of strength, serviceability, stability and fire resistance
shall be determined from Clause 4.1.4.
3.3 DESIGN FOR LIMIT STATES
3.3.1 Design for strength
Once composite action is fully developed (i.e., after Construction Stage 5 when f ′cj ≥ f′ c),
the composite beam shall be proportioned and the shear connection between the steel beam
and the concrete slab detailed, so that, under the design actions for the strength limit state
(S*), the design capacity (φR u ) at every cross-section satisfies the following inequality:
 Standards Australia
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AS 2327.1—2003
29
φRu ≥ S *
where
φ
=
an appropriate capacity factor not greater than the value given in
Table 3.1
Ru
=
the relevant nominal capacity determined in accordance with Sections 6,
8 and 9
S*
=
the corresponding design action effect determined in accordance with
Section 5 for the appropriate design loads
TABLE 3.1
CAPACITY FACTOR FOR THE STRENGTH LIMIT STATE
Type of action effect
Capacity factor ( φ)
Bending
(a)
Propped construction: Construction Stage 5
(see Clause 4.2.3)
0.70
(b)
All other cases
0.90
Vertical shear
0.90
Longitudinal shear
(a)
Concrete slab
0.70
(b)
Shear connectors
0.85
3.3.2 Design for serviceability
The composite beam shall be designed so that, under the design actions for the
serviceability limit state, its deflection and vibration, as well as cracking of the concrete
slab, shall each be controlled in accordance with Section 7.
3.3.3 Design for durability
The durability requirements of AS 3600 and AS 4100 shall be satisfied for the concrete slab
and the steel beam respectively. For composite slabs, the manufacturer’s recommendations
regarding the durability of profiled steel sheeting shall be followed. Concrete cover to shear
connectors shall satisfy the requirements of Clause 8.4.4.
3.3.4 Design for fire resistance
Where appropriate, the composite beam shall be designed and detailed in accordance with
Section 10 so that its fire-resistance period for structural adequacy is not less than the
corresponding period specified for the required fire-resistance level. The concrete slab
component of the composite beam shall be designed and detailed in accordance with
Appendix G, so that its fire-resistance periods for structural adequacy, insulation and
integrity are not less than the corresponding periods specified by the required fire-resistance
level.
3.3.5 Design by prototype testing
Notwithstanding the requirements of Clauses 3.3.1 and 3.3.2, a composite beam may be
designed for strength or deflection, or both, by load testing two or more prototypes in
accordance with Clause 12.3, using appropriate design loads determined from Clause 4.1.4.
If this alternative procedure is adopted, the beam shall also be designed for vibration,
durability and fire resistance, as necessary, in accordance with the requirements of
Clauses 3.3.2, 3.3.3 and 3.3.4 respectively.
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AS 2327.1—2003
30
SECT ION
4
ACT I ONS AND
S IT UA T I ONS
DES I GN
4.1 GENERAL
4.1.1 Actions
The design of the member for the limit states specified in Clause 3.3 shall take account of
the action effects directly arising from the following actions:
(a)
Permanent and imposed, wind, snow and earthquake loads determined in accordance
with AS/NZS 1170.1, AS/NZS 1170.2, AS/NZS 1170.3 and AS 1170.4, respectively.
(b)
Construction loads, determined in accordance with Appendix F.
(c)
Other specific loads, as required.
Uniformly distributed imposed loads for the in-service condition may be reduced in
accordance with Clause 4.1.3.
4.1.2 Other actions
Any other action that may significantly affect the stability, strength, or serviceability of the
member, including but not limited to the following, shall be taken into account:
(a)
Removal of construction props.
(b)
Foundation movement.
(c)
Temperature changes and gradients.
(d)
Transient dynamic actions.
(e)
Shrinkage or creep of concrete.
4.1.3 Reduction of uniformly distributed imposed loads
Uniformly distributed imposed loads acting on the composite beam during the in-service
condition may be reduced, when appropriate, in accordance with AS/NZS 1170.1, taking
into account the magnitude of the tributary area (see Clause 5.3.5).
NOTE: Tributary area (A) should be calculated in accordance with Clause 5.3.5 considering
whether the concrete slab exhibits either one-way or two-way action.
4.1.4 Design loads
Except as noted herein, the design loads for the relevant limit state shall be determined
from the appropriate combinations of actions specified in AS/NZS 1170.0 and AS 1170.4
and, if applicable, shall include any other actions, appropriately factored.
4.2 CONSTRUCTION STAGES
4.2.1 General
For the purpose of determining the design actions, action effects and member capacities,
due account shall be taken of the construction stages given in Clauses 4.2.2 and 4.2.3,
which are affected by the development of composite action (see also Appendix F).
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AS 2327.1—2003
4.2.2 Prior to development of composite action
Until such time as the concrete in the slab has attained a compressive strength of 15 MPa,
no composite action between the steel beam and the concrete shall be assumed. This
encompasses Construction Stages 1 to 4, which are distinguished as follows:
(a)
Stage 1 Period between when the steelwork is erected, and the formwork is placed
and, if appropriate, fixed to the steel beams.
(b)
Stage 2 Period between the end of Construction Stage 1 and immediately prior to the
commencement of casting the slab concrete.
(c)
Stage 3 Period between commencement of casting the slab concrete and its initial set
under the prevailing site conditions.
(d)
Stage 4 Period from the initial set of the slab concrete until its compressive strength
(estimated by f′ cj) reaches 15 MPa.
NOTES:
1 An estimate of the characteristic compressive strength of the slab concrete, at an age of ‘j’
days (f′ cj) may be obtained from compression tests on cylinder specimens of the concrete
that have been subjected to the same curing conditions as the slab for that period, using
the following equation:
f cj′ = f cmj − 1.65 s ≤ f c′
where
2
f′ cj
=
the estimated characteristic compressive strength of concrete at j days
fcmj
=
the average compressive strength of sample cylinders after j days of site
curing
s
=
the standard deviation of sample strengths of the grade of concrete used
The 7 day mean strength of normal class concrete can be estimated using AS 1379. For
example, if the concrete has been continuously moist cured, an average compressive
strength of not less than 15 MPa may be expected in 7 days by Grades N32 and stronger
grades; however, if 15 MPa is required at a time less than 7 days, special class concrete
may need to be specified.
4.2.3 After development of composite action
Once the concrete in the slab has attained a compressive strength of 15 MPa, development
of composite action between the steel beam and the concrete may be assumed. This
encompasses Construction Stages 5 and 6, which are distinguished as follows:
(a)
Stage 5 Period from the end of Construction Stage 4 until the characteristic strength
of the slab concrete reaches its specified design value (f′c ) (see Note 1).
(b)
Stage 6 Period following the end of Construction Stage 5 to the end of construction
immediately prior to the in-service condition (see Note 2).
NOTES:
1
Props to either the concrete slab or steel beam may be removed during Construction Stage 5,
provided the strength of the composite beam is checked in accordance with Clause 3.3.1.
2
By the end of Construction Stage 6 any props present should have been removed.
3
The construction stages defined in Clauses 4.2.2 and 4.2.3 assume that the principal
construction activities and processes are as shown in Figure F1, Appendix F.
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AS 2327.1—2003
32
SECT ION 5
EFFECT I V E
DES IG N ACT I O N EF FECT S
DES IG N
SECT ION AND
FOR STRENGTH
5.1 GENERAL
The effective section of a composite beam cross-section shall be determined in accordance
with Clause 5.2 and used for strength design in accordance with Section 6. The effective
section shall be determined for each potentially critical cross-section defined in Clause 6.3,
except at the ends of the beam where the steel beam alone shall be assumed to act.
The design action effects arising from the design loads specified in Clause 4.1.4 for the
strength limit state after the development of composite action, (i.e., Construction Stages 5
and 6 as defined in Clause 4.2.3 and for the in-service condition) shall be determined in
accordance with the procedure given in Clause 5.3.
NOTE: The design action effects relevant here are the design vertical shear force V* and the
design bending moment M*.
5.2 EFFECTIVE SECTION OF A COMPOSITE BEAM CROSS-SECTION
5.2.1 General
Allowance shall be made for the in-plane shear flexibility (shear-lag) of a concrete
compression flange, by using an effective width of flange calculated in accordance with
Clause 5.2.2.
The region of the concrete slab within the effective width shall be designed for longitudinal
shear in accordance with Section 9.
The portion of the steel beam considered to form part of the effective section of the
composite beam cross-section shall be determined in accordance with Clause 5.2.3.
Any vertical construction joint that falls within the effective width shall be designed in
accordance with Section 9, taking into account the surface condition of the original concrete
face. Any concrete that falls above a horizontal construction joint (e.g., when a screed is
poured on top of an existing slab) shall be ignored when calculating the effective section,
unless the joint is designed for longitudinal shear and the specified compressive strength f′c
of the concrete is at least as great as that assumed in design for the remainder of the slab.
NOTE: The procedure that should be followed is shown in Figure E2 of Appendix E.
5.2.2 Effective width of concrete compression flange
5.2.2.1 Solid slab
Where the concrete flange is a solid slab, its effective width (b cf ) shall be calculated as the
sum of the distances be measured on each side of the centre-line of the steel beam (see
Figure 5.2.2.1), where b e is in each case the smallest of—
(a)
L ef /8, where Lef is the effective span of the beam calculated in accordance with
Clause 5.3.3;
(b)
in the case of a concrete slab with a free edge (i.e., an edge beam situation), either the
perpendicular distance to the edge measured from the centre-line of the beam, or
6 times the overall depth D c of the concrete slab plus half the width of the steel beam
flange bsf1 ; and
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(c)
AS 2327.1—2003
in the case of a concrete slab that spans between two steel beams (i.e., either an edge
beam or internal beam situation), either half the centre-to-centre distance between the
steel beams or 8 times the overall depth D c of the concrete slab plus half the width of
the steel beam flange bsf1 .
When a slab has pockets or cut-outs within its effective width then, at the cross-sections of
concern, bcf shall be reduced by the width they encroach into this region.
FIGURE 5.2.2.1 EFFECTIVE WIDTH OF CONCRETE COMPRESSION FLANGE AT A
COMPOSITE BEAM CROSS-SECTION — SOLID SLAB CASE
5.2.2.2 Composite slab
Where the concrete flange is a composite slab, the effective width of the flange (b cf )—
(a)
for the portion of the slab above the ribs, shall be determined in accordance with
Clause 5.2.2.1; and
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AS 2327.1—2003
(b)
34
for the portion of the slab within the depth of the ribs, shall be taken as the value
obtained from (a) multiplied by the factor λ, where—
λ
=
1.0, for 0 < θ ≤ 15°;
λ
=
(b cr cos2 θ)/s r , for 15° < θ ≤ 60°;
λ
=
0, for θ > 60°; and
θ
=
the acute angle between the sheeting ribs and the longitudinal axis of
the steel beam (see Figure 5.2.2.2 including Note).
. . .5.2.2.2(1)
NOTE: The value of θ should be determined for each side of the beam where the orientation of the sheeting is
different.
FIGURE 5.2.2.2 EFFECTIVE WIDTHS OF CONCRETE PORTIONS OF
A COMPOSITE SLAB
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AS 2327.1—2003
5.2.3 Effective portion of steel beam
5.2.3.1 General
The effective portion of the steel beam cross-section at the strength limit state shall be
determined in accordance with—
(a)
Clause 5.2.3.2 if the entire depth of the steel beam is in tension; or
(b)
Clause 5.2.3.3 if only part of the depth of the steel beam is in tension (see Note 1).
The part of the steel beam subject to tension at the strength limit state shall be determined
from Section 6.
For fabricated steel beams, or steel beams with an additional plate welded to the bottom
flange, the welds connecting the plate elements of the beam together shall be designed to
transmit the shear forces that develop on account of the axial tensile forces assumed to be
carried by these elements (see Note 2).
The effect of holing of the steel beam may be ignored in the following cases:
(i)
Where holes are drilled in the top flange to accommodate high-strength structural
bolts used as shear connectors in accordance with Section 8.
(ii)
Where holes are drilled or cut in the web so that their greatest internal dimension Lw
satisfies—
L w/d 1 ≤ 0.10 (see Note 3)
. . . 5.2.3.1(1)
NOTES:
1
If there is partial shear connection at the cross-section of concern (i.e., β < 1), Item (b) will
always apply.
2
Particular attention needs to be given to this issue when designing cross-sections close to
where an additional plate welded to the bottom flange is terminated.
3
It is beyond the scope of this Standard to provide a method for designing composite beams
with larger web penetrations. A method for designing composite beams with larger web
penetration is given in Reference 9, Appendix I.
5.2.3.2 Tension in whole of steel beam (β = 1)
The whole of the steel beam section at a cross-section of a composite beam shall be
assumed to be effective.
5.2.3.3 Compression in part of steel beam (β ≤ 1)
When part of the top flange, or the top flange and part or all of the web of the steel beam is
in compression, account shall be taken of the slenderness (λe) of each of these plate
elements either partially or fully in compression, in order to determine the effective portion
of the steel beam (see Note 1). The plate element slenderness (λ e) is given by—
 b  fy
 t  250
λe =  
. . . 5.2.3.3(1)
where
b
=
clear width of the element outstand from the face of the supporting
plate element or the clear width of the element between faces of
supporting plate elements
t
=
element thickness
fy
=
yield stress of plate element used in design
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36
Steel beams with slender plate elements shall not be used (see Note 1). The effective
portion of a steel beam with either compact (see Note 2) or non-compact (see Note 3) plate
elements shall be calculated according to the following:
(a)
If the top flange and web are compact, the entire steel section shall be assumed to be
effective.
(b)
If the outstand of the flange is non-compact, the effective flange width shall be the
maximum width for which the flange is compact.
(c)
If the web is non-compact, the effective portion of the web may be determined in
accordance with Figure 5.2.3.3(a) in which the length ‘x’ is ineffective. Alternatively,
the effective portion of the web may be determined approximately as shown in
Figure 5.2.3.3(b) where the effective thickness of the effective web (t ′w) is calculated
ignoring the ineffective portion of the web in the compressive zone. Cold-formed,
rectangular hollow steel sections, manufactured in accordance with AS 1163, shall
have a compact top flange, calculated in accordance with Table 5.1 and assuming a
uniform compressive stress distribution across the width of the flange.
NOTES:
1
2
It is assumed that the entire width of the bottom flange will be effective.
Slender plate elements are such that λe > λ ey, where values of the yield slenderness limit
λ ey are given in Table 5.1.
3
Compact plate elements are such that λ ep ≥ λe, where values of the plasticity slenderness
limit λep are given in Table 5.1.
4
Non-compact plate elements are such that λey ≥ λe > λep.
FIGURE 5.2.3.3 EFFECTIVE PORTION OF STEEL BEAM WITH
NON-COMPACT TOP FLANGE OR WEB
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AS 2327.1—2003
TABLE 5.1
PLATE ELEMENT PLASTICITY AND YIELD SLENDERNESS LIMITS
Plate
element
Longitudinal
edges
supported
Residual
stresses
Plasticity limit
Yield limit
(see Notes)
λ ep
One
SR
HR
LW, CF
HW
10
9
8
8
16
16
15
14
Flange
Both
SR
HR
LW, CF
HW
30
30
30
30
45
45
40
35
Web
One
any
82
115
For
1.0≥rp ≥0.5:
For
1.0 ≥ re ≥0.5:
111
322
( 4.7 rp − 1)
(3.6re + 1)
For rp <0.5:
41/r p
For re <0.5:
57.5/r e
Flange
Web
Both
any
Stress distribution
λ ey
Stress
distribution
LEGEND:
SR = stress relieved
HR = hot-rolled or hot-finished
CF = cold-formed
LW = lightly welded
HW = heavily welded
NOTES:
1
Welded members with compressive residual stresses of less than 40 MPa may be considered to be lightly
welded.
2
The value of the parameter re , which defines the position of the elastic neutral axis, should be calculated from
the elastic stress distribution for the steel section alone, ignoring the presence of the concrete slab.
5.3 CALCULATION OF DESIGN ACTION EFFECTS DUE TO DESIGN LOADS
5.3.1 General
For the purpose of complying with the requirements for the strength limit state, the design
action effects in a simply supported composite beam and its connections shall be
determined using the calculation procedure in Clause 5.3.4.
NOTE: It is outside the scope of this Standard to provide rules for the design of the composite
beam if the steel beam is propped during Construction Stages 5 and 6 when it will act as a
continuous member.
5.3.2 Definitions
For the purpose of Clauses 5.3.3 to 5.3.5, the following definitions apply:
(a)
Effective span the span used in the calculation of design action effects allowing for
different end support conditions of the composite beam (see Clause 5.3.3).
(b)
Tributary area the plan area from which dead and live loads acting on the slab will
be assumed to be received by a supporting composite beam (see Clause 5.3.5).
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5.3.3 Effective span
The effective span of a composite beam (Lef ) shall be taken as the distance between the
lines of action of the vertical reactions at the ends of the beam (where bending moment is
assumed to equal zero). When the lines of action of the beam reactions are unknown, their
position may be determined in accordance with Paragraph H1, Appendix H.
5.3.4 Calculation procedure
The composite beam shall be considered to be simply supported with an effective span L ef .
The design loads calculated in accordance with Section 4 shall be assumed to act over the
tributary area defined in Clause 5.3.5, taking into account the effect of any propping to the
slab. When calculating the design action effects for the composite beam, the effects of
construction sequence shall be ignored, whereby it shall be assumed that the design loads
are entirely resisted by the action of the composite beam.
NOTES:
1
It is assumed that at the strength limit state, the stresses in the composite beam section being
checked for strength are not affected by the sequence of construction or loading, and that they
can be calculated using rectangular stress block theory in accordance with Section 6.
2
If the capacity of a composite beam is being checked for Construction Stages 5 and 6, slab
propping may affect the tributary area determination; however, the design action effects M*
and V* are calculated without regard for the sequence of construction or loading.
3
If the capacity of a composite beam is being checked for the in-service condition, any
previous slab propping will neither affect the tributary area determination nor the calculation
of M* and V*.
5.3.5 Tributary area
In the absence of a more accurate determination, the tributary area of a composite beam for
the strength limit state may be determined in accordance with Paragraph H2, Appendix H.
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39
SECT ION
6
DES IG N
AS 2327.1—2003
F OR
STRENGTH
6.1 GENERAL
A composite beam shall be designed for strength in accordance with Clause 6.2 using the
effective section(s) determined in accordance with Section 5 and the degree of shear
connection (β ) defined in Clause 1.4.3 and calculated as shown in Figure 6.1.
FIGURE 6.1 CALCULATION OF DEGREE OF SHEAR CONNECTION β AT
COMPOSITE BEAM CROSS-SECTION
6.2 DESIGN
6.2.1 General
The design shall be conducted to satisfy the limit state requirements specified in
Clause 6.2.2 following the procedure defined in Clause 6.2.3.
6.2.2 Limit state requirements
The composite beam shall be designed so that at every transverse cross-section—
(a)
the design vertical shear capacity (φV u ) is not less than the design vertical shear force
(V*) (i.e., φV u ≥ V*); and
(b)
the design moment capacity (φM bv ) is not less than the design bending moment (M*)
during construction and for the in-service condition (i.e. φM bv ≥ M*).
The above requirements shall be deemed to be satisfied at every cross-section if they are
shown to be satisfied at each of the relevant potentially critical cross-sections defined in
Clause 6.3.
6.2.3 Design procedure
6.2.3.1 General
A composite beam shall be designed for strength in accordance with either one of the
following, as appropriate:
(a)
The general procedure given in Clause 6.2.3.3.
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(b)
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The simplified procedure given in Clause 6.2.3.2, only if—
(i)
the beam is prismatic and uniformly loaded;
(ii)
the mid-span cross-section satisfies the requirements for complete shear
connection; and
(iii) M bc ≤ 2.5 Ms .
6.2.3.2 Simplified procedure
The simplified procedure for strength design is as follows:
(a)
Calculate the effective section of the composite beam in accordance with Clause 5.2
assuming β = 0.
(b)
Calculate the design action effects M* and V* at the mid-span cross-section and beam
ends, respectively, in accordance with Clause 5.3.
(c)
Calculate the design vertical shear capacity (φV u ) in accordance with Clause 6.4.1,
and check that φV u ≥ V* (see Clause 6.2.2(a)).
(d)
Calculate the nominal moment capacity M bc (and the corresponding value of F cc) in
accordance with Paragraph D2.3.2, Appendix D and check that φM bc ≥ M*
(Clause 6.2.2(b)).
(e)
Calculate the nominal shear capacity of a single shear connector (f vs) in accordance
with Section 8, and hence determine the minimum number of shear connectors (n ic)
required between the mid-span cross-section and each end of the beam from the
following relationship (see Note 3 to Clause 6.2.3.3):
n ic = F cc / f ds
. . . 6.2.3.2
NOTE: This Equation only holds if all the shear connectors have the same design shear
capacity f ds , otherwise the equation needs to be modified accordingly. Also, in accordance
with Clause 8.3.4, fds is a function of nic and hence the calculation of n ic is an iterative
process.
(f)
Distribute the shear connectors as uniformly as possible along the beam, satisfying
the detailing requirements in Clause 8.4 appropriate to the particular type and size of
shear connectors.
(g)
Determine the quantity of longitudinal shear reinforcement in accordance with
Section 9.
Alternatively, the procedure given in Clause 6.2.3.3 may be followed.
6.2.3.3 General procedure
The general procedure for strength design is as follows:
(a)
Identify all potentially critical cross-sections in accordance with Clause 6.3.
(b)
Calculate the effective section at each potentially critical cross-section in accordance
with Clause 5.2.
(c)
Calculate the design action effects M* and V* at each potentially critical cross-section
in accordance with Clause 5.3.
(d)
For each potentially critical cross-section, calculate the design vertical shear capacity
( φV u) in accordance with Clause 6.4.1, check that φV u ≥ V* in accordance with
Clause 6.2.2(a) and calculate the value of the shear ratio γ (= V*/ φV u).
(e)
Identify those potentially critical cross-sections for which M* > 0 and the shear
ratio (γ) falls within the ranges—
(i)
0.0 ≤ γ ≤ 0.5; and
(ii)
0.5 < γ ≤ 1.0.
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AS 2327.1—2003
(f)
For the appropriate range and value of γ, calculate the relationship between
φM bv and β in accordance with Clause 6.4.2 at each corresponding potentially critical
cross-section (see Note 2).
(g)
From Clause 6.5, calculate the minimum degree of shear connection (β i) at each
potentially critical cross-section (i) so that φM bv ≥ M* in accordance with
Clause 6.2.2(b), where φM bv and M* are the appropriate values at the particular
cross-section. The degree of shear connection at the cross-section of maximum
bending moment β m shall not be less than 0.5 (see Clause 6.6).
(h)
With the values of β i determined from Step (g), calculate Fcp.i from Paragraph D2.3.3
of Appendix D with the applicable value of Fcc.i from Paragraph D2.3.2 for each
potentially critical cross-section (i).
(i)
Calculate the nominal shear capacity of a single shear connector (f vs) in accordance
with Section 8, and hence determine the minimum number of shear connectors (n i )
required between each potentially critical cross-section for which M* > 0 and the
ends of the steel beam from the following relationship (see Note 3):
n i = F cp.i/f ds
. . . 6.2.3.3(1)
(j)
Distribute the shear connectors along the beam in accordance with Clause 6.6.
(k)
Determine the required quantity of longitudinal shear reinforcement in accordance
with Section 9.
NOTES:
1
Use of the general design procedure is illustrated in Reference 1, Appendix I.
2
M bv is the general symbol for nominal moment capacity either in the presence or absence of
vertical shear, and may be used to represent symbols such as Mb , and M bc.
3
This Equation only holds if all the shear connectors have the same design shear capacity f ds. If
not, the equation will need to be modified accordingly. Also, in accordance with Clause 8.3.4,
f ds is a function of ni and hence the calculation of ni is an iterative process.
6.3 POTENTIALLY CRITICAL CROSS-SECTIONS
For the purpose of Clause 6.2.3.3, the following transverse cross-sections of a composite
beam shall be deemed to be potentially critical:
(a)
Sections of maximum design bending moment (M*) and sections of maximum design
vertical shear force (V*).
NOTE: In the case of beams with a constant maximum moment region, the potentially
critical cross-sections with respect to bending are to be taken as those at the ends of the
constant moment region.
(b)
Sections where external bending moments or concentrated vertical loads are applied
to the beam, for example where other beams frame into the composite beam.
(c)
Sections where there is a change in the cross-sectional geometry of either the slab or
the steel beam, for example, at changes in flange width or thickness, at penetrations
in the web of the steel beam, or at a notched section.
(d)
Sections midway between the section(s) of maximum design bending moment and the
adjacent end(s) of the beam where the nominal moment capacity (M bc) corresponding
to complete shear connection exceeds 2.5 times the nominal moment capacity (Ms) of
the steel beam.
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6.4 CALCULATION OF DESIGN VERTICAL SHEAR CAPACITY (φ V u ) AND
DESIGN MOMENT CAPACITY (φM bv) AS A FUNCTION OF DEGREE OF SHEAR
CONNECTION (β )
6.4.1 Design vertical shear capacity (φ V u )
Unless it can be demonstrated that the concrete slab contributes to the transverse shear
capacity of the composite beam, φV u shall be calculated in accordance with AS 4100,
assuming that only the steel beam is effective.
6.4.2 Design moment capacity (φM bv)
The design moment capacity of a composite beam cross-section (φM bv) shall be calculated
as a function of the degree of shear connection (β ) in accordance with—
(a)
Appendix D (Paragraph D2) if γ ≤ 0.5; or
(b)
Appendix D (Paragraph D3) if 0.5 < γ ≤ 1.
Prior to the full development of composite action during Construction Stage 5, i.e.
when 15≤ f′cj < f′c , the design moment capacity (φM bv) shall be calculated by replacing f′ c
with f′cj in all relevant equations in Appendix D, and using the appropriate value of φ given
in Table 3.1 depending on whether construction is propped or unpropped.
6.5 CALCULATION OF MINIMUM DEGREE OF SHEAR CONNECTION β i AT
POTENTIALLY CRITICAL CROSS-SECTIONS
6.5.1 General
The linear approximations to the φM bv −β relationships determined in accordance with
Clause 6.4 may be used to calculate the minimum degree of shear connection β i at a
potentially critical cross-section i in order to satisfy the strength requirement φM bv ≥ M*
(Clause 6.2.2(b)) at that cross-section. The appropriate equations are given in Clause 6.5.2
for cross-sections where γ ≤ 0.5, and in Clause 6.5.3 for cross-sections where γ > 0.5.
6.5.2 Cross-sections where γ ≤ 0.5
At cross-sections where γ ≤ 0.5, the minimum degree of shear connection β i at each
potentially critical cross-section i may be calculated directly using any one of the following
equations, as appropriate, depending on the magnitude of design bending moment M* in
relation to the magnitudes of the design moment capacities φMs and φM b.5 (i.e., φMb at
β = 0.5) at the cross-section being considered (see Figure D2.2(b), Appendix D):
(a)
For M* ≤ φMs
βi = 0
(b)
For φM s < M* ≤ φMb.5
βi =
(c)
M * − φM s
≥0
2 ( φM b.5 − φ M s )
. . . 6.5.2(1)
For φM b.5 < M* ≤ φM bc
βi =
 Standards Australia
M * + φM bc − 2φM b.5
2 ( φM bc − φM b.5 )
. . . 6.5.2(2)
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AS 2327.1—2003
6.5.3 Cross-sections where 0.5 < γ ≤ 1.0
At cross-sections where γ > 0.5, the minimum degree of shear connection (β i) at each
potentially critical cross-section i may be calculated directly using either of the following
equations, as appropriate, depending on the magnitude of design bending moment M* in
relation to the magnitudes of the design moment capacities φM bv.0, φM bv.ψ and φM bvc (i.e.,
φM bv at β = 0, ψ and 1.0, respectively) at the cross-section being considered (see
Figure D3.3(b), Appendix D):
(a)
For 0 ≤ β i ≤ ψ
βi =
[M * −(2γ − 1)φM sf − 2(1 − γ )φM s ]ψ
(1 − 2γ )φM sf + (2γ − 1)φM bfc − 2(1 − γ )φM s + 2(1 − γ )φM b.ψ
. . . 6.5.3(1)
≥ 0
(b)
For ψ < β i
βi = ψ +
(1 − ψ )[M * −2(1 − γ )φM b.ψ − (2γ − 1)φM bfc ]
2(1 - γ )(φM bc − φM b.ψ )
. . . 6.5.3(2)
If the calculated value of β i is greater than 1.0, the section is inadequate.
6.6 DISTRIBUTION OF SHEAR CONNECTORS BETWEEN POTENTIALLY
CRITICAL CROSS-SECTIONS AND BEAM ENDS
6.6.1 General
Composite beams designed for strength using the general procedure in Clause 6.2.3.3 shall
have their shear connectors distributed in accordance with Clause 6.6.2.
For the purpose of Clause 6.6.2, the number of shear connectors ( ni′ ) considered fully
effective in contributing to the design moment capacity (φM bv ) of potentially critical
cross-section i shall be calculated in accordance with Clause 6.6.3.
6.6.2 Distribution of shear connectors
The shear connectors shall be distributed longitudinally according to the following rules:
(a)
The degree of shear connection at the cross-section of maximum design bending
moment (β m) shall not be less than 0.5. In the case of a beam with a constant
maximum moment region, this requirement shall only apply to the cross-section at the
middle of the region.
(b)
The number of shear connectors ( ni′ ) considered to contribute to the design moment
capacity ( φM bv ) of potentially critical cross-section i shall equal or exceed n i , where n i
is determined from Clause 6.2.3.3.
(c)
The shear connectors should be distributed as uniformly as possible between any
cross-section of maximum design bending moment (M*) and the adjacent end/s of the
beam, or between adjacent potentially critical cross-sections, as appropriate.
(d)
The detailing requirements given in Clause 8.4 appropriate to the particular type and
size of shear connector used in the beam shall be satisfied.
6.6.3 Calculation of number of shear connectors ( ni′ )
The number of shear connectors ( ni′ ) considered to contribute to the design moment
capacity ( φMbv ) of potentially critical cross-section i shall equal the lesser number of
connectors provided on each side of the cross-section. This shall not exceed n ic , where n ic is
the minimum number of shear connectors required to develop complete shear connection at
cross-section i, ignoring the presence of shear force as given by Equation 6.2.3.2. Shear
connectors provided between any other potentially critical cross-section and a beam end, in
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AS 2327.1—2003
44
excess of the number required to develop complete shear connection at that cross-section,
shall be ignored when calculating ni′ .
NOTE: Particular attention should be paid to satisfying this latter requirement when the steel
beam is non-prismatic due to the presence of a notch, web penetration or flange plate. Then the
calculation is performed by successively considering segments of the beam between adjacent
potentially critical cross-sections, moving out from a beam end as demonstrated by the example
in Figure 6.6.3.
NOTES:
1
PCC stands for potentially critical cross-section.
2
The number of shear connectors contributing to the design moment capacity at PCCs 3, 4 and 5 is
influenced by the reduced cross-sectional area of the steel beam at the web penetration.
3
It has been assumed that at least 25 connectors are effective and contribute to the design moment capacity
of the maximum moment cross-section on the right-hand side of PCC 5.
FIGURE 6.6.3 EXAMPLE SHOWING CALCULATION OF n′ i
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SECT ION
7
DES IG N
F OR
AS 2327.1—2003
SERV ICE AB I L I T Y
7.1 GENERAL
Composite beams shall be designed for serviceability by limiting vertical deflection and
controlling cracking and vibration in accordance with Clauses 7.2 to 7.4 respectively.
7.2 DEFLECTION CONTROL
7.2.1 Definitions
For the purpose of this Section, the following definitions apply:
(a)
Total deflection—the deflection arising from short-term and long-term loading effects
and shrinkage, which occurs from when the steel beam is erected until the end of the
design life.
NOTES:
(b)
1
If total deflection is measured from the top of the concrete slab, then it is zero at the point
in time when the slab is screeded level (i.e., during Construction Stage 3), in which case
it does not include any deflection from Construction Stages 1 to 3. Alternatively, total
deflection may be measured from the steel beam soffit relative to the horizontal, which
may be considered important when the floor is left visually exposed from beneath. In this
case, precambering the steel beam can reduce the total deflection.
2
For composite slabs, suggested upper limits for the deflection of the profiled steel
sheeting at the completion of Construction Stage 3 are given in Appendix C.
Incremental deflection—the deflection arising from short-term and long-term loading
effects and shrinkage, which occurs after a chosen stage in the life of the structure
(e.g., after the attachment of brittle elements) up until the end of the design life.
7.2.2 Deflection control
The deflection of composite beams under in-service conditions shall be controlled as
follows:
(a)
Limits for the calculated total and incremental deflection of the beam shall be chosen
appropriate to the structure and its intended use (see Note).
(b)
The calculated deflections shall not exceed the chosen limits when the beam supports
the short-term and long-term design loads for serviceability determined in accordance
with Clause 4.1.4.
(c)
The deflections of a beam shall be calculated using either a refined method in
accordance with Clause 7.2.3 or the simplified method in accordance with
Clause 7.2.4.
NOTE: Suggested upper limits for total and incremental deflections are given in Appendix C.
7.2.3 Refined method
A refined method of calculation shall make allowance for the following factors, as deemed
appropriate:
(a)
Changes in beam section (i.e., steel beam or composite) during Construction Stages 1
to 6.
(b)
Expected loading history during Construction Stages 1 to 6 and the in-service
condition.
(c)
Changes in cross-section along the length of the beam.
(d)
Flexural cracking and tension stiffening.
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(e)
Creep and shrinkage of the concrete.
(f)
Longitudinal slab reinforcement.
(g)
Slip at the interface between the slab and the steel beam.
(h)
Yielding in the steel beam (see Note).
(i)
Residual stresses in the steel beam.
(j)
Temperature changes.
(k)
End restraints (axial or rotational or both).
(l)
Precamber of the steel beam.
NOTE: This Standard permits localized yielding of the steel beam under serviceability loads
provided its effects are taken into account in the calculation of deflections.
7.2.4 Simplified method
The deflection may be calculated using the design procedure given in Appendix B, which
makes allowance for the following:
(a)
Changes in beam section (i.e., steel beam or composite) during Construction
Stages 1 to 6.
(b)
Expected loading history during Construction Stages 1 to 6 and the in-service
condition (see Note 1).
(c)
Changes in cross-section along the length of the beam (see Note 2).
(d)
Flexural cracking.
(e)
Creep and shrinkage of the concrete.
(f)
Slip at the interface between the slab and the steel beam.
(g)
Precamber of the steel beam.
For composite beams incorporating a steel beam consisting of a cold-formed rectangular
hollow section manufactured in accordance with AS 1163, the immediate deflection
components calculated using the simplified method shall be increased by 20% (see Notes 3
and 4).
The simplified method shall not be used if the maximum stress in the steel beam (either
tensile or compressive), calculated ignoring residual stresses, exceeds 0.9 f yb either during
construction or under serviceability loads during the in-service condition.
NOTES:
1
The load combinations for the serviceability limit state assumed in the formulation of the
simplified method have been taken from AS/NZS 1170.0 as G + ψ s Q and G + ψl Q during the
in-service condition.
2
Beams with holes drilled or cut in the web, where their greatest internal dimension L w
exceeds L w /d1 = 0.10, should not be designed using the simplified method.
3
This allowance is made to take into account the effects of factors including residual stresses
in the steel tubing and additional shear connection flexibility associated with local
deformations of the tube walls.
4
The additional deflections in composite beams incorporating cold-formed rectangular hollow
sections are reported in Reference 2, Appendix I.
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AS 2327.1—2003
7.3 CRACK CONTROL
7.3.1 Slab continuity transverse to span
Cracking in the concrete flange of composite beams, which is due to continuity of the slab
transverse to the span of the beam, shall be deemed to be controlled if the requirements of
AS 3600 for crack control of slabs are satisfied for both the primary and secondary
directions.
7.3.2 Slab continuity in the direction of the span
Cracking in the concrete flange at the ends of simply-supported composite beams may
occur where there is continuity of the slab in the direction of the span at those locations
(e.g., where secondary beams frame into both sides of a primary beam). Appropriate
measures shall be taken to control or prevent such cracking, particularly where
minimization of crack widths is an important consideration (e.g., for durability of the floor
or satisfactory appearance of any applied floor finish).
NOTE: Accounting for the continuity of the slab beyond the beam support is outside the scope of
this Standard; however, the problem is normally avoided by using unpropped construction. Some
guidance on this matter is given in Reference 3, Appendix I.
7.4 VIBRATION CONTROL
The response of a floor system incorporating composite beams to an applied source of
vibration shall be controlled so that there will be—
(a)
no damage to the beam or the structure of which it is a part;
(b)
no unanticipated restrictions imposed on the intended use of the structure; and
(c)
not more than minimal discomfort to the occupants of the structure.
The above requirements may be satisfied by means of the following, used either singly or in
combination:
(i)
Dynamically isolating the applied source from the floor.
(ii)
Limiting the frequencies of the relevant modes of vibration of the floor to values
significantly different to the anticipated excitation frequencies.
(iii) Ensuring that sufficient mass is mobilized in the relevant vibration modes such that
the acceleration response is limited to an acceptable level.
(iv)
Providing sufficient damping to limit near-resonant acceleration response to an
acceptable level.
NOTE: Guidance on the design of floor systems for occupant-induced vibration is given in
References 4 and 10, Appendix I.
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48
SECT ION
8
DES IG N O F
CONNECTORS
SHEAR
8.1 GENERAL
Shear connectors for attachment to the top flange of the steel beam shall comply with the
requirements of Clause 8.2. Their design shear capacity shall be determined from
Clause 8.3, and they shall be detailed in accordance with Clause 8.4. The strength grade of
the slab concrete shall not exceed 40 MPa.
NOTE: A limit is placed on the strength grade because shear connector ductility tends to reduce
as concrete compressive strength increases.
The shear connectors may be used in the presence of profiled steel sheeting. The profiled
steel sheeting shall be defined as either closed-rib or open-rib (see Clause 1.4.3) which can
affect the strength (see Clause 8.3.3) and the detailing of the shear connectors (see
Clause 8.4).
8.2 SHEAR CONNECTORS
8.2.1 Types
Shear connectors shall be limited to one or more of the following types (see also
Figure 8.2):
(a)
Headed studs.
(b)
Channels.
(c)
High-strength structural bolts.
The geometry of each type of shear connector shall conform with Clause 8.2.2.
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AS 2327.1—2003
DIMENSIONS IN MILLIMETRES
FIGURE 8.2 SHEAR CONNECTOR DETAILS
8.2.2 Geometry
8.2.2.1 Headed studs
Standard-type headed studs with a nominal shank diameter of either 15.9 mm or 19 mm
shall be used. They shall comply with the dimensions and tolerances given in AS 1554.2 for
this type of shear connector.
The minimum overall height of studs after welding, measured from the top of the stud to the
top surface of the top flange of the steel beam, shall be 4.0 times the nominal shank
diameter dbs . In composite slabs, the studs shall extend not less than 40 mm above the top of
the ribs of the profiled steel sheeting (see Figure 8.2 (a)).
8.2.2.2 Channels
Channel shear connectors shall be cut only from sections designated 100TFC or 100PFC in
AS/NZS 3679.1, and shall have a nominal length (l) of 50 mm. Their minimum and
maximum lengths shall be 50 mm and 60 mm, respectively (see Figure 8.2 (b)).
8.2.2.3 High-strength structural bolts
High-strength structural bolts shall be M20 in size and fitted with one nut above and one
below the top flange of the steel beam. After tightening, at least one clear thread shall show
above the top nut and at least one thread plus the thread run-out shall show below the
bottom nut. Washers may be omitted. The overall height of the bolts measured between the
top of the bolt head and the top surface of the flange of the steel beam shall not be less than
100 mm (see Figure 8.2 (c)).
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8.3 SHEAR CAPACITY OF SHEAR CONNECTORS
8.3.1 General
When cast in normal-weight or lightweight concrete, the nominal shear capacity (f vs) of
single shear connectors, of the types described in Clause 8.2.1, shall be determined from
Clause 8.3.2 for solid slabs and Clause 8.3.3 for composite slabs.
The design shear capacity (f ds) of a shear connector acting either by itself or as an element
of a set of shear connectors shall be calculated in accordance with Clause 8.3.4.
8.3.2 Nominal shear capacity in solid slabs
8.3.2.1 Headed studs
The nominal shear capacity (f vs) of either an automatically welded or manually welded
headed stud shall be determined as the lesser value from the following equations:
f vs = 0.63 d 2 f ; or
bs
uc
. . . 8.3.2.1(1)
f vs = 0.31 d 2
bs
. . . 8.3.2.1(2)
f cj′ E c
where
f uc = characteristic tensile strength of shear-connector material, not to exceed
500 MPa when substituted into Equation 8.3.2.1(1)
E c = elastic modulus of slab concrete corresponding to the relevant value of f′cj
= ρ 1.5 0.043
c
f cj′
During Construction Stage 6 and the in-service condition, the values for the nominal shear
capacity (f vs) of headed-stud shear connectors in normal-weight concrete, of a standard
strength grade (f′c = 20, 25, 32 or 40 MPa), are as given in Table 8.1 for the standard shank
diameters of 15.9 mm and 19.0 mm.
During Construction Stage 5 (15 MPa ≤ f′cj < f′c), the value for f vs shall be calculated
either—
(a)
as the lesser value directly from Equations 8.3.2.1(1) and 8.3.2.1(2) for both normalweight and lightweight concrete; or
(b)
for normal-weight concrete, from Table 8.1 by linear interpolation between the values
of f vs in the two adjacent columns between which f′cj falls.
TABLE 8.1
NOMINAL SHEAR CAPACITY f vs OF HEADED-STUD SHEAR
CONNECTORS IN NORMAL-WEIGHT CONCRETE
f vs (kN) for
f c′ (MPa) of —
Stud diameter
dbs (mm)
f vs (kN) for
f cj′ = 15 MPa
20
25
32
40
19.0
60
75
89
93
93
15.9
42
53
62
65
65
NOTE: The tabulated values of f vs have been calculated from Equations 8.3.2.1(1) and 8.3.2.1(2)
assuming ρc = 2400 kg/m 3 and using the minimum value permitted by AS 1554.2 for fuc, which is
410 MPa.
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AS 2327.1—2003
8.3.2.2 Channels
During Construction Stage 6 and the in-service condition, the values for the nominal shear
capacity (f vs) of channel shear connectors in normal-weight concrete, of a standard strength
grade (f′c = 20, 25, 32 or 40 MPa), shall be determined from Table 8.2.
During Construction Stage 5 (15 MPa ≤ f′cj < f′ c), the value for f vs in normal-weight
concrete shall be calculated from Table 8.2 by linear interpolation between the values of f vs
in the two adjacent columns between which f′ cj falls.
For channels in lightweight concrete, f vs shall be taken as 80% of the value determined
above for normal-weight concrete of the same grade.
TABLE 8.2
NOMINAL SHEAR CAPACITY f vs OF CHANNEL SHEAR CONNECTORS IN
NORMAL-WEIGHT CONCRETE
f vs (kN) for f′ c (MPa) of—
f vs (kN) for
f′ cj = 15 MPa
20
25
32
40
100 TFC × 50/250
76
95
100
110
125
100 PFC × 50/300
76
95
100
110
125
Size × length/grade
8.3.2.3 High-strength structural bolts
During Construction Stage 6 and the in-service condition, the values for the nominal shear
capacity (f vs) of M20 high-strength structural bolt shear connectors in normal-weight
concrete, of a standard strength grade (f ′c = 20, 25, 32 or 40 MPa), shall be determined from
Table 8.3.
During Construction Stage 5 (15 MPa ≤ f′cj < f′ c), the value for f vs in normal-weight
concrete shall be calculated from Table 8.3 by linear interpolation between the values of f vs
in the two adjacent columns between which f′ cj falls.
For high-strength structural bolts in lightweight concrete f vs shall be taken as 80% of the
value determined above for normal-weight concrete for the corresponding strength.
TABLE 8.3
NOMINAL SHEAR CAPACITY f vs OF HIGH STRENGTH STRUCTURAL BOLT
SHEAR CONNECTORS IN NORMAL-WEIGHT CONCRETE
Size/grade
M20/8.8
f vs (kN) for f′ c (MPa) of—
dbs (mm)
f vs (kN) for
f′ cj = 15 MPa
20
25
32
40
20
67
83
98
118
126
NOTE: The tabulated values of f vs have been calculated from Equations 8.3.2.1(1) and 8.3.2.1(2) assuming
ρc = 2400 kg/m 3 and using the maximum value permitted by AS 1252 for fuc, which is 500 MPa.
8.3.3 Nominal shear capacity in composite slabs
The nominal shear capacities (f vs) of the different types of shear connectors in composite
slabs shall be the same as those given in Clause 8.3.2 for solid slabs. When headed studs are
placed in pairs between sheeting ribs of an open-rib profile deemed perpendicular to the
steel beam, the value of fvs shall be determined from Clause 8.3.2.1 using a value of f uc of
not greater than 410 MPa.
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8.3.4 Design shear capacity
The design shear capacity (fds) of a shear connector acting as an element of set of n shear
connectors is given by—
f ds = φ k n f vs
. . . 8.3.4(1)
where the value of φ is given in Table 3.1, and the load-sharing factor (k n ), given as a
function of n, is—
(
k n = 1.18 − 0.18 / n
)
. . . 8.3.4(2)
The number of shear connectors (n) shall be taken as the lesser number of shear connectors
provided between each end of the beam and the cross-section being designed.
8.4 DETAILING OF SHEAR CONNECTORS
8.4.1 Longitudinal detailing
For beams with solid or composite slabs, the shear connectors shall be detailed along the
length of the beam according to the following requirements:
(a)
Longitudinal distribution The shear connectors shall be longitudinally distributed
between potentially critical cross-sections and beam ends as uniformly as possible in
accordance with Clause 6.6, while complying with the longitudinal spacing
requirements of Clause 8.4.1(b).
(b)
Longitudinal spacing limits The longitudinal spacing of shear connectors shall not
exceed 4.0 times the overall depth (D c) of the slab, or 600 mm, whichever is the
lesser.
In solid slabs and in composite slabs with sheeting deemed parallel to the steel beam,
the longitudinal spacing shall be—
(i)
not less than 5.0 times the shank diameter (d bs) of the shear connectors between
centres of headed studs or high-strength structural bolts, ignoring staggering
(see Figure 8.4.1(A)(a)); or
(ii)
not less than 100 mm clear between adjacent edges of channels (see
Figure 8.4.1(A)(b)).
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AS 2327.1—2003
DIMENSIONS IN MILLIMETRES
FIGURE 8.4.1(A) LONGITUDINAL SPACING OF SHEAR CONNECTORS
IN SOLID SLABS
(c)
Proximity to ribs of open-rib profiles Where the slab is composite with the profiled
steel sheeting ribs passing over the steel beam, and automatically welded headed
studs are used, the distance between adjacent faces of a shear connector and a
sheeting rib measured parallel to the longitudinal axis of the beam shall be not less
than 60 mm (see Figure 8.4.1(B)).
FIGURE 8.4.1(B) PLACEMENT OF AUTOMATICALLY WELDED HEADED STUDS IN
COMPOSITE SLABS INCORPORATING OPEN-RIB PROFILE WITH RIBS PASSING OVER
STEEL BEAM
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(d)
54
Proximity to ribs of closed-rib profiles Where the slab is composite with the profiled
steel sheeting ribs passing over the steel beam, and automatically welded headed
studs are used, there shall be no restriction on the distance between adjacent faces of
a shear connector and a sheeting rib measured parallel to the longitudinal axis of the
beam.
NOTE: There should be sufficient clearance between adjacent faces of the steel sheeting rib
and the stud being welded to permit the ceramic ferrule used in the welding operation to fit
flat on the sheeting pan, and avoid any conflict of the welding gun with the steel rib.
8.4.2 Transverse detailing
Each transverse cross-section of the beam where shear connectors are placed shall be
detailed according to the following requirements:
(a)
Maximum number of shear connectors per transverse cross-section or sheeting
pan The number of shear connectors per transverse cross-section (n x ) shall not
exceed the maximum values given in Table 8.4 according to the type of shear
connector and whether the slab is solid or composite.
For composite slabs incorporating an open-rib profile with the sheeting ribs deemed
perpendicular to the steel beam (see Clause 9.4.2.2), and automatically welded headed
studs are fired through the sheeting, the tabulated values are the maximum number of
connectors permitted between any two consecutive ribs.
TABLE 8.4
MAXIMUM NUMBER OF SHEAR CONNECTORS PER CROSS-SECTION (n x )
Shear connector type
Solid slab
Composite slab
Automatically welded headed studs
3
2
Manually welded headed studs
3
2
High-strength structural bolts
2
2
Channels
1
1
(b)
Transverse spacing of headed studs or high-strength structural bolts Headed studs
and high-strength structural bolts shall be spaced transversely so that the clear
distance between their heads is not less than 1.5 times the shank diameter of the shear
connector (dbs).
(c)
Proximity to profiled steel sheeting Where the slab is composite, the minimum
clearance between the shear connector and the nearest part of a sheeting rib or end of
an open-rib profile shall be—
(i)
for automatically welded headed studs, in accordance with Figure 8.4.2(a);
(ii)
for manually welded headed studs and high-strength structural bolts, in
accordance with Figure 8.4.2(b) and (c); and
(iii) for channels, in accordance with Figure 8.4.2(d).
NOTE: For closed-rib profile steel sheeting, the limits on minimum distance in Figure 8.4.2
do not apply.
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Shear connector
type
AS 2327.1—2003
Distance to sides of sheeting ribs
(mm)
Distance to ends of sheeting
(mm)
(a) Automatically
welded headed
studs
(i)
Sheeting discontinuous with a gap
between sheets, and shear
connectors welded directly to the
steel beam
(ii)
Sheeting discontinuous without a
gap between sheets, and shear
connectors welded through the
sheeting.
FIGURE 8.4.2(in part) TRANSVERSE DETAILING OF SHEAR CONNECTORS IN
PROXIMITY TO PROFILED STEEL SHEETING
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Shear connector
type
(b)
Manually welded
headed studs
(c)
High-strength
structural bolts
(d)
Channels
56
Distance to sides of sheeting ribs
(mm)
Distance to ends of sheeting
(mm)
NOTE: For Cases (b), (c) and (d), the sheeting is discontinuous on both sides of the shear connector.
FIGURE 8.4.2(in part) TRANSVERSE DETAILING OF SHEAR CONNECTORS IN
PROXIMITY TO PROFILED STEEL SHEETING
8.4.3 Attachment details
8.4.3.1 General
For steel beams consisting of either an I, Tee, channel, or fabricated rectangular hollow
section, the thickness of the steel beam flange to which a welded stud or high-strength
structural bolt, as appropriate, is attached shall not be less than 0.4 times the shank diameter
of the shear connector (d bs), except that in the case of welded studs this restriction does not
apply if the studs are welded directly over the web. For channel shear connectors, the
thickness of flange to which it is welded shall be not less than 6 mm.
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AS 2327.1—2003
DIMENSIONS IN MILLIMETRES
FIGURE 8.4.3.1 SHEAR CONNECTOR MINIMUM EDGE DISTANCES
For steel beams consisting of a cold-formed rectangular hollow section manufactured in
accordance with AS 1163, not more than one shear connector shall be attached at a
transverse cross-section. The thickness of the section to which automatically welded studs
are to be attached shall be not less than 0.4dbs . Headed studs or channels may be manually
welded to cold-formed rectangular hollow sections not less than 4 mm in thickness.
The distance between the edge of a shear connector and the adjacent edge of the flange to
which it is connected shall be not less than that shown in Figure 8.4.3.1. These distances
may need to be increased to provide the required end bearing for the sheeting.
Headed studs shall be welded using either automatically timed stud welding equipment in
accordance with AS 1554.2 (i.e., ‘automatically welded studs’) or by manual fillet welding
in accordance with Clause 8.4.3.3 (i.e., ‘manually welded studs’). Only automaticallywelded studs may be welded through profiled steel sheeting in accordance with
Clause 8.4.3.2.
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8.4.3.2 Automatically welded headed studs
Automatically welded headed studs shall be welded in accordance with AS 1554.2. Studs
shall not be welded through longitudinal stiffeners.
NOTE: It follows from this requirement and from Clause 8.4.1(c) that, depending on the angle
between the sheeting ribs and the longitudinal axis of the steel beam, the studs may only be
placed in the central flat area of the sheeting pans of an open-rib profile, as shown in
Figure 8.4.1(B).
8.4.3.3 Manually welded headed studs
Manually welded headed studs shall be attached directly to the flange of the steel beam, and
not through profiled steel sheeting. The surface and stud base preparation, minimum fillet
size and the welding procedure for attaching headed studs shall be in accordance with
AS 1554.2.
NOTE: It is recommended that if a manual metal-arc welding procedure is adopted, then
3.25 mm E48XX electrodes should be used in a two-pass operation.
8.4.3.4 Channels
Channels shall be welded directly to the flange of the steel beam, and not through profiled
steel sheeting. The minimum weld details for attaching channels are shown in
Figure 8.2.2(b). Welding shall be carried out in accordance with AS/NZS 1554.1.
8.4.3.5 High-strength structural bolts
High-strength structural bolts shall be fitted into 20 mm finished diameter holes. The holes
shall be—
(a)
round and be machine-flame cut;
(b)
drilled full size;
(c)
sub-punched 3 mm undersized and reamed to size; or
(d)
punched full size.
A punched hole shall only be permitted in material whose yield stress f y does not exceed
360 MPa and whose thickness does not exceed 5600/f y mm. The minimum edge distance
shall comply with AS 4100.
The bolts shall be snug tight as defined in AS 4100.
All material between the nuts shall be steel, except that profiled steel sheeting, or any other
type of steel component, which may be compressible, shall not be permitted.
8.4.4 Minimum concrete cover for durability
For protection against corrosion of the shear connectors, the cover to the nearest concrete
surface shall be—
(a)
to any unprotected edge of the slab, not less than 75 mm; and
(b)
to the top surface of the slab, not less than the value given in Table 8.5 for the
appropriate concrete characteristic compressive strength f′c and exposure
classification defined in AS 3600.
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TABLE 8.5
MINIMUM TOP COVER TO SHEAR CONNECTORS
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Exposure
classification
f ′ c = 20
MPa
25
32
40
A1
20
20
20
20
A2
—
25
20
20
B1
—
—
30
25
B2
—
—
—
35
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SECT ION
60
9
TRANSFE R OF L ONG I T UD I NA L
SHEAR IN C ONCRETE
9.1 GENERAL
Sufficient longitudinal shear reinforcement shall be provided in the concrete flange to
prevent longitudinal shear failure of the flange arising from the transfer of longitudinal
forces through the shear connectors.
The reinforcement may be designed in accordance with Clause 9.3. Alternatively, the
reinforcement, including any contribution of the profiled steel sheeting, may be designed by
load testing two or more prototype beams in accordance with Clause 12.3, using appropriate
design loads determined from Clause 4.1.
NOTE: Throughout the Section it is assumed that all the shear connectors in a beam have the
same nominal shear capacity f vs . If this is not the case, the design procedure given in Clause 9.3.2
can be readily modified.
9.2 DEFINITIONS
For the purpose of this Section, the definitions below apply.
9.2.1 Connector group
The shear connectors grouped at a transverse cross-section of a beam.
9.2.2 Connector set
The shear connectors between a transverse cross-section and an end of a beam.
9.2.3 Longitudinal shear plane
A plane in a slab over which a longitudinal shear failure can potentially occur.
9.2.4 Longitudinal shear surface
A surface comprising either a single longitudinal shear plane, or two or more intersecting
longitudinal shear planes, over which a shear failure can possibly occur leading to part of
the concrete slab separating from the composite beam.
9.2.5 Longitudinal shear reinforcement
Reinforcement (not necessarily horizontal) that crosses one or more longitudinal shear
planes.
9.3 DESIGN
9.3.1 Limit state requirement
The longitudinal shear reinforcement in a slab shall be designed so that at any longitudinal
shear surface, the design longitudinal shear capacity per unit length of beam (φV L ) shall not
be less than the design longitudinal shear force per unit length of beam (V* L )
(i.e., φV L ≥ V* L ).
This requirement shall be deemed to be satisfied at every conceivable longitudinal shear
surface located within the effective width of a slab, provided it can be shown to be satisfied
at every occurrence of the relevant types of shear surfaces defined in Clause 9.4.1.
Reinforcement for Types 1, 2 and 3 longitudinal shear surfaces shall satisfy the
requirements of Clause 9.3.2. Reinforcement for Type 4 longitudinal shear surfaces shall
satisfy the requirements of Clause 9.8.
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9.3.2 Design procedure
For Types 1, 2 and 3 longitudinal shear surfaces, the longitudinal shear reinforcement in the
concrete slab of a composite beam shall be designed according to the following procedure
(see also Figure E4 of Appendix E):
(a)
At each potentially critical transverse cross-section i of the beam identified at Step (e)
in Clause 6.2.3.3 at which M* > 0, determine the lesser number of shear connectors
(n i.min ) that have been provided between the cross-section and the ends of the beam.
(b)
Calculate the design shear capacity (f ds) of the connectors in accordance with
Clause 8.3.4, based on the largest value of n i.min determined from Step (a) for all the
potentially critical transverse cross-sections. This value of fds shall be assumed for
every connector in the beam.
(c)
Identify those regions along the length of the beam where there is a variation in either
the number of connectors per connector group (n x) or the longitudinal spacing
between adjacent connector groups (sc).
(d)
Calculate values of the total design longitudinal shear force per unit length (V* L.tot)
corresponding to the value of f ds and the different values of n x and s c determined from
Steps (b) and (c) using the relationship—
V * L.tot =
n x f ds
sc
. . . 9.3.2
(e)
Identify the different types of longitudinal shear surfaces defined in Clause 9.4.1
applicable to each situation being designed, i.e., each combination of n x and sc with
its corresponding value of V* L.tot , and calculate the shear surface perimeter length (u)
for each case in accordance with Clause 9.4.2. Any other cross-sectional differences,
such as a change in the transverse spacing between connectors, shall also be taken
into account.
(f)
Calculate the design longitudinal shear force per unit length (V* L ) acting on each
longitudinal shear surface applicable to each situation being designed in accordance
with Clause 9.5.
(g)
Calculate the cross-sectional area of the longitudinal shear reinforcement (Asv )
required at each shear surface in longitudinal shear so that φV L ≥ V* L in accordance
with Clause 9.3.1, where the nominal longitudinal shear capacity per unit length (V L )
shall be calculated in accordance with Clause 9.6, and the value of the capacity factor
φ is given in Table 3.1.
(h)
Detail the longitudinal shear reinforcement in accordance with Clause 9.7.
9.4 LONGITUDINAL SHEAR SURFACES
9.4.1 Shear surface types
For determining longitudinal shear transfer, four types of longitudinal shear surfaces shall
be considered in design (see Figure 9.4.1) as follows:
(a)
Type 1 A plane that passes directly through the concrete in a solid or composite slab
at right angles to its top surface.
(b)
Type 2 A combination of three orthogonal planes, which enclose the shear
connectors in a solid or composite slab, two of which emanate from the slab bottom
face.
(c)
Type 3 A combination of three planes, which enclose the shear connectors in a
composite slab, either one or two of which emanate from the top corners of the steel
sheeting ribs which cross the transverse cross-section.
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(d)
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Type 4 A horizontal plane that passes across the tops of the steel sheeting ribs in a
composite slab in which the sheeting ribs are deemed perpendicular to the beam,
locally avoiding the shear connectors by passing over their tops, and which extends
from the outside vertical face of a slab outstand in a composite edge beam and
continues some distance into the adjacent slab.
NOTE: Type 4 longitudinal shear failure is described in Reference 5, Appendix I.
DIMENSIONS IN MILLIMETRES
FIGURE 9.4.1 LONGITUDINAL SHEAR SURFACE TYPES
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9.4.2 Shear surface perimeter length (u)
9.4.2.1 General
The length of the perimeter (u) of the intersection between a Type 1, 2 or 3 longitudinal
shear surface and a transverse slab cross-section shall be determined in accordance with this
Clause.
9.4.2.2 Orientation of profiled steel sheeting
The orientation of profiled steel sheeting as it affects the perimeter length of Type 1 and
Type 3 shear surfaces shall be taken into account as follows (see also Figure 5.2.2.2):
(a)
When the acute angle θ between the steel ribs and the longitudinal axis of the steel
beam is less than or equal to 15°, the sheeting shall be deemed to be parallel to the
beam.
(b)
When θ exceeds 15°, the sheeting shall be deemed to be perpendicular to the beam.
9.4.2.3 Type 1 shear surfaces
At least the following occurrences of Type 1 shear surfaces shall be considered in design
(see Figure 9.4.2.3):
(a)
At the outside faces of shear connector groups.
(b)
Where longitudinal shear reinforcement is curtailed.
(c)
Directly over each steel sheeting rib deemed parallel to the steel beam in accordance
with Clause 9.4.2.2(a).
The perimeter length of Type 1 shear surfaces shall be assumed to equal one of the
following as appropriate:
(i)
D c for solid slabs.
(ii)
D c for composite slabs with sheeting ribs deemed perpendicular to the steel
beam.
(iii) (Dc−h r) directly over ribs for composite slabs with sheeting ribs deemed parallel
to the steel beam.
(iv)
D c between ribs for composite slabs with sheeting ribs deemed parallel to the
steel beam.
9.4.2.4 Type 2 shear surfaces
The perimeter length of Type 2 shear surfaces shall be assumed to equal (b x + 2h c), where—
bx
=
the overall width across the tops of all the shear connectors in the crosssection (see Figure 9.4.1(a)); and
hc
=
the overall height of the shear connectors above the top flange of the
steel beam.
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FIGURE 9.4.2.3 LOCATIONS OF TYPE 1 SHEAR SURFACES
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9.4.2.5 Type 3 shear surfaces
The perimeter length of Type 3 shear surfaces shall be assumed to equal the lesser of the
values shown in Figure 9.4.2.5.
FIGURE 9.4.2.5 POSSIBLE PERIMETER LENGTHS OF TYPE 3 SHEAR SURFACES
9.5 DESIGN LONGITUDINAL SHEAR FORCE (V* L)
At a cross-section of a composite beam, the design longitudinal shear force per unit length
(V* L ) shall be assumed to vary linearly from a maximum on each side of the centre-line of
the steel beam to zero at the extremities of the effective width of the concrete slab (see
Figure 9.5).
Accordingly, the design longitudinal shear force per unit length (V* L ), acting on a Type 1,
shear surface centred distance x from an extremity of the effective width, shall be
determined from Equation 9.5(1) and on Types 2 and 3 surfaces from Equation 9.5(2).
 x 
V *L =   V *L.tot
 bcf 
. . . 9.5(1)
V *L = V *L.tot
. . . 9.5(2)
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FIGURE 9.5 DISTRIBUTION OF LONGITUDINAL SHEAR FORCE FOR
TYPE 1 SHEAR SURFACES
9.6 NOMINAL LONGITUDINAL SHEAR CAPACITY (V L)
The nominal longitudinal shear capacity per unit length (V L ) of a Type 1, 2 or 3 shear
surface shall be calculated as the lesser value given by the following equations:
(a)
V L = u(0.36 √f′c) + 0.9Asv f yr
. . . 9.6(1)
(b)
V L = 0.32 f′c u
. . . 9.6(2)
where
u
= shear surface perimeter length in millimetres, determined in
accordance with Clause 9.4.2
f′ c
= characteristic compressive strength of the concrete, in megapascals
A sv = total cross-sectional area of longitudinal shear reinforcement crossing
the shear surface (see Figure 9.4.1(a)), in mm 2 per mm length of beam
f yr
= the yield strength of the longitudinal shear reinforcement, in
megapascals
Profiled steel sheeting shall not be considered to contribute to Asv .
NOTE: The units of V L determined from the above equations are newtons per millimetre length of
beam. Designers should ensure that V* L and φ V L are expressed in the same units when comparing
them for the purpose of satisfying Clause 9.3.1.
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AS 2327.1—2003
9.7 TYPES 1, 2 AND 3 LONGITUDINAL SHEAR REINFORCEMENT
9.7.1 General
The longitudinal shear reinforcement that crosses a Type 1, 2 or 3 shear surface shall be
detailed as follows:
(a)
The cross-sectional area per metre length of beam (Asv ) shall not be less than that
required by Clause 9.3.2, except that for Type 2 and Type 3 shear surfaces, neither
shall the area be less than that required by Clause 9.7.2. The reinforcement required
for each connector group shall be placed on either or both sides of the connectors of
that group within a distance sc /2 measured along the beam.
(b)
It shall be anchored beyond the appropriate sides of the shear surface in accordance
with Clause 9.7.3.
(c)
Its top face shall be at least 30 mm below the top of the shear connectors in the case
of Type 2 and Type 3 shear surfaces (see Figure 9.4.1(a)).
Flexural reinforcement in the slab placed transverse to the longitudinal axis of the beam
may be included as part or all of the reinforcement for longitudinal shear transfer, provided
that it meets all of these requirements as necessary.
9.7.2 Minimum longitudinal shear reinforcement for Type 2 and 3 shear surfaces
The minimum cross-sectional area of longitudinal shear reinforcement required for shear
transfer (Asv.min ) across Type 2 and 3 shear surfaces, in square millimetres per metre length
of beam, shall be calculated according to the following equation:
Asv.min = 800u / f yr
. . . 9.7.2
NOTE: The area of bottom bars (A sp.b) is required to be not less than A sv.min /2, as indicated in
Figure 9.4.1(a).
9.7.3 Anchorage of longitudinal shear reinforcement
Longitudinal shear reinforcement should extend beyond each side of the shear plane for at
least the development length for tension (Lsy.t) determined in accordance with AS 3600. If
the distance available for anchorage (L) is less than Lsy.t , the area of longitudinal shear
reinforcement considered to be effective for use in Equation 9.6(1) shall be taken as
A sv L/L sy.t. In no case shall L be less than 15 db for straight deformed bars, where d b is the
nominal diameter of the bar.
9.8 TYPE 4 LONGITUDINAL SHEAR REINFORCEMENT
9.8.1 Locations
Reinforcement for Type 4 shear surfaces shall be provided in edge beams with profiled steel
sheeting deemed perpendicular to the steel beam in accordance with Clause 9.4.2.2 and
which extends across the top flange of the steel beam (see Figure 9.4.1(b)), at locations
where there are—
(a)
two welded stud shear connectors in a sheeting pan, irrespective of the width of the
slab outstand; or
(b)
one welded stud shear connector in a sheeting pan, and the slab outstand is less than
600 mm wide measured from the vertical outside edge of the slab to the edge of the
nearest shear connector.
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9.8.2 Detailing
Longitudinal shear reinforcement provided at the locations specified in Clause 9.8.1 and
detailed in accordance with the following shall be deemed to develop the required
resistance across Type 4 shear surfaces. Alternative detailing may be used provided that it
can be demonstrated, by adequate test data, that the alternative prevents this mode of
failure.
DIMENSIONS IN MILLIMETRES
FIGURE 9.8.2 TYPE 4 LONGITUDINAL SHEAR REINFORCEMENT
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The reinforcement shall satisfy all of the following:
(a)
The reinforcement shall cross the shear surface and be composed of one or more of—
(i)
stirrups or ties, which cross perpendicular to the shear surface and enclose
longitudinal bars; and
(ii)
welded-wire fabric, with the longitudinal wires cranked such that they make an
angle of between 30° and 90° with the shear surface.
(b)
The maximum transverse spacing of consecutive parallel bars or wires which form the
stirrups, ties or fabric shall be 150 mm measured perpendicular to the length of the
beam (see Figure 9.8.2).
(c)
Reinforcement, of nominal tensile capacity (f yr Asv ) not less than 20 kN per bar or
wire, shall be used. At each location, at least two such bars or wires shall cross the
shear surface every 150 mm width of slab. The reinforcement shall extend into the top
and bottom of the slab above and below the shear surface, respectively, and be
adequately anchored to develop a stress of at least 0.5f yr in the reinforcement at the
level of the shear surface. A width of slab at least equal to 400 mm shall be
reinforced. The reinforcement shall be centred over the steel beam, except that when
the slab outstand width is too narrow for this to occur, it shall be placed as close to
the slab edge as concrete covers will allow.
NOTE: Detailing of Type 4 longitudinal shear reinforcement is described in Reference 6,
Appendix I.
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SECT ION
10
DES IG N F OR
RES ISTANCE
F I RE
10.1 REQUIREMENTS
This Section applies to composite beams, with either a solid or composite slab, required to
have a fire-resistance level (FRL).
For protected composite beams, the thickness of protection material (h i ) shall be not less
than that required to attain the period of structural adequacy (PSA) specified by the
required FRL.
For unprotected composite beams, the exposed surface area to mass ratio (ksm ) shall be not
greater than that required to attain the PSA specified by the required FRL.
The period of structural adequacy (PSA) for a composite beam shall be determined in
accordance with Clause 10.3.
Connections and web penetrations shall be designed and constructed so that the fireresistance level of the composite beam is not impaired. This may be achieved by complying
with the requirements of Clause 10.9.
10.2 DEFINITIONS
For the purpose of this Section, the definitions below apply.
10.2.1 Exposed surface area to mass ratio
The ratio of the surface area exposed to the fire to the mass of steel, noting that in the case
of members with fire protection material applied, the exposed surface area is to be taken as
the internal surface area of the fire protection material.
10.2.2 Fire exposure condition
(a)
Three-sided fire exposure condition A composite beam in which the top face of the
steel beam is in contact with a solid or composite slab in a specific configuration (see
Clause 10.8).
(b)
Four-sided fire exposure condition A steel member or element exposed to fire on all
sides.
10.2.3 Fire protection system
The fire protection material and its method of attachment to the composite member.
10.2.4 Fire-resistance level (FRL)
The fire-resistance periods for structural adequacy, insulation and integrity, expressed in
that order in minutes, which are specified by the authority for the member or element.
10.2.5 Fire-resistance period
The elapsed time, in minutes, for a prototype member, or element of building construction,
to reach the relevant failure criterion specified in AS 1530.4, when tested in accordance
with that Standard.
10.2.6 Insulation
The ability of a fire separating member to limit the surface temperature on one side of the
member when exposed to fire on the opposite side.
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10.2.7 Integrity
The ability of a fire separating member to resist the passage of flames or hot gases through
the member when exposed to fire on one side.
10.2.8 Period of structural adequacy (PSA)
The time (t), in minutes, for the member to reach the limit state of structural adequacy.
10.2.9 Prototype
A test specimen representing a member and its fire protection system, which is subjected to
the standard fire test.
10.2.10 Standard Fire Test
The fire-resistance test specified in AS 1530.4.
10.2.11 Stickability
The ability of the fire protection system to remain in place as the member deflects under
load during a fire test, as specified in AS 1530.4.
10.2.12 Structural adequacy
The ability of the member to maintain its structural function when exposed to fire.
10.3 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY
The period of structural adequacy (PSA) shall be determined using one of the following
methods:
(a)
By calculating—
(i)
the limiting temperature of the steel (T l ) in accordance with Clause 10.4; and
(ii)
the PSA as the time from the start of the test (t) to the time at which the
limiting steel temperature is attained in accordance with Clause 10.5 for
protected members and Clause 10.6 for unprotected members.
(b)
By direct application of a single test in accordance with Clause 10.7.
(c)
By other calculation methods as defined in Clause 10.10.
10.4 DETERMINATION OF LIMITING TEMPERATURE OF THE STEEL
The limiting temperature of the steel T l shall be calculated as follows:
Tl = 905 − 690 rf
. . . 10.4
where
r f = the maximum value along the length of the beam of the ratio of the design
bending moment (M*), under the design load for fire, to the design moment
capacity ( φM bv) at room temperature
10.5 DETERMINATION OF TIME AT WHICH LIMITING TEMPERATURE IS
ATTAINED FOR PROTECTED MEMBERS
10.5.1 Methods
The time (t) at which the limiting temperature (T l) is attained shall be determined by
calculation on the basis of a suitable series of fire tests in accordance with Clause 10.5.2 or
from the results of a single test in accordance with Clause 10.5.3.
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10.5.2 Temperature based on test series
10.5.2.1 Method of calculation
Calculation of the variation of steel temperature with time shall be by interpolation of the
results of a series of fire tests using the regression analysis equation specified in
Clause 10.5.2.2 subject to the limitations and conditions of Clause 10.5.2.3.
10.5.2.2 Regression analysis
The relationship between temperature (T) and time (t) for a series of tests shall be
calculated by least-squares regression as follows:
 h 
hT 
 T 

t = k 0 + k l hi + k 2  i  + k3 T + k 4 hi T + k5  i  + k6 
k
k
k
 sm 
 sm 
 sm 
. . . 10.5.2.1
where
t
= time from the start of the test, in minutes
k 0 to k 6 = regression coefficients
hi
= thickness of fire protection material, in millimetres
T
= average steel temperature calculated using all thermocouples as shown in the
figure illustrating ‘Recommended location of thermocouples on typical
structural sections’ in AS 1530.4, in degrees Celsius, T > 250°C
ksm
= exposed surface area to mass ratio, in square metres per tonne (m2 /t).
10.5.2.3 Limitations and conditions on use of regression analysis
Test data to be utilized in accordance with Clause 10.5.2.1 shall satisfy the following:
(a)
Tested prototypes shall be protected with board, sprayed, blanket or similar insulation
materials having a dry density less than 1000 kg/m 3 .
NOTE: There is insufficient test data available to make comprehensive recommendations on
interpolation for members protected with other materials such as intumescent coatings.
(b)
All prototypes shall be protected with the same fire protection system.
(c)
All prototypes shall have the same fire exposure condition and shall fall within a
single group as defined in Clause 10.8.
(d)
The test series shall include at least nine tests.
(e)
The test series may include prototypes that have not been loaded provided that
stickability has been demonstrated.
The steel temperature for a composite beam may be obtained from a regression equation
provided that—
(i)
the fire protection system is the same as that of the test series;
(ii)
the fire exposure condition is the same as that of the test series;
(iii) the temperature can be obtained by interpolation within the window defined by the
test series as shown in Figure 10.5.2.3; and
(iv)
the data is obtained from either steel or composite member prototypes.
The regression equation obtained for one fire protection system may be applied to another
system using the same fire protection material and the same fire exposure condition
provided that stickability has been demonstrated for the second system.
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AS 2327.1—2003
A regression equation obtained using prototypes with a four-sided fire exposure condition
may be conservatively applied to a composite beam provided that stickability has been
demonstrated for the three-sided fire exposure condition.
FIGURE 10.5.2.3 DEFINITION OF WINDOW FOR INTERPOLATION LIMITS
10.5.3 Temperature based on single test
The variation of steel temperature with time measured in a single Standard Fire Test may be
used without modification provided—
(a)
the fire protection system is the same as the prototype;
(b)
the fire exposure condition is the same as the prototype;
(c)
the fire protection material thickness is equal to or greater than that of the prototype;
(d)
the exposed surface area to mass ratio is equal to or less than that of the prototype;
and
(e)
where the prototype has been submitted to a Standard Fire Test in an unloaded
condition, stickability has been separately demonstrated.
10.6 DETERMINATION OF TIME AT WHICH LIMITING TEMPERATURE IS
ATTAINED FOR UNPROTECTED MEMBERS
The time (t) at which the limiting temperature is attained shall be calculated using the
following expression:
 0.433T 

t = − 5.2 + 0.0221T + 

 ksm 
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where
t
= time from the start of the test, in minutes
T
= steel temperature, in degrees Celsius, 500°C ≤ T ≤ 750°C
ksm = exposed surface area to mass ratio, in square metres per tonne, 2 ≤ ksm ≤ 35
For temperatures below 500°C, linear interpolation shall be used based on the time at 500°C
and an initial temperature of 20°C at t = 0.
10.7 DETERMINATION OF PSA FROM A SINGLE TEST
The period of structural adequacy (PSA) determined in accordance with AS 1530.4 from a
single test may be applied without modification provided—
(a)
the fire protection system is the same as the prototype;
(b)
the fire exposure condition is the same as the prototype;
(c)
the fire protection material thickness is equal to or greater than that of the prototype;
(d)
the exposed surface area to mass ratio is less than or equal to that of the prototype;
(e)
the conditions of support are the same as the prototype and the restraints are not less
favourable than those of the prototype; and
(f)
the value of r f of the member (see Clause 10.4) is less than or equal to that of the
prototype.
10.8 THREE-SIDED FIRE EXPOSURE CONDITION
Beams subject to a three-sided fire exposure condition shall be considered elements of a
single group when both of the following conditions are satisfied:
(a)
 highest in group 
 ≤ 1.25
For concrete density : 
 lowest in group 
(b)
 largest in group 
 ≤ 1.25
For slab depth (Dc ) : 
 smallest in group 
Blocking of rib voids in profiled steel sheeting which passes over the steel beam may be
ignored for grouping purposes.
10.9 CONNECTIONS AND WEB PENETRATIONS
10.9.1 Connections
Connections shall be protected with the maximum thickness of fire protection material
required for any of the members framing into the connection, to achieve their respective fire
resistance levels. This thickness shall be maintained over all connection components,
including bolt heads, welds and splice plates.
10.9.2 Web penetrations
The thickness of fire protection material at and adjacent to web penetrations (see
Figure 10.9.2) shall be the greatest of—
(a)
that required for the area above the penetration considered as a three-sided fire
exposure condition (ksm1 );
(b)
that required for the area below the penetration considered as a four-sided fire
exposure condition (ksm2 ); or
(c)
that required for the section as a whole considered as a three-sided fire exposure
condition (k sm ).
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This thickness shall be applied over the full beam depth and shall extend each side of the
penetration for a distance at least equal to the steel beam depth and not less than 300 mm.
FIGURE 10.9.2 WEB PENETRATIONS
10.10 DETERMINATION OF PERIOD OF STRUCTURAL ADEQUACY BY
OTHER CALCULATION METHODS
The period of structural adequacy of a composite beam may be predicted by a suitable
method of calculation which takes into account the following:
(a)
The variation of the mechanical properties of steel with temperature in accordance
with AS 4100.
(b)
The variation of the mechanical properties of concrete and of steel reinforcement with
temperature in accordance with AS 3600.
(c)
The temperature distribution in the member obtained from a rational method of
analysis confirmed by test data.
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SECT ION
11
CONSTRUCT IO N
11.1 GENERAL
The requirements of this Section, where appropriate, shall be satisfied for each of the six
construction stages defined in Clause 4.2. Due allowance shall be made for differential
deflections between structural elements to avoid uncertain load distributions, possible
damage, or undue distortion.
11.2 CONSTRUCTION SEQUENCE AND LOADS
The construction sequence shall conform to that detailed on the drawings or in the project
specification (see Clause 1.6.2). It shall be assured during all stages of construction that the
live loads (including stacked materials) do not cause a more adverse effect on the structure
than that assumed in design (see Clause 4.2).
11.3 STEELWORK
11.3.1 Fabrication and erection
Fabrication and erection of steelwork shall be in accordance with AS 4100.
11.3.2 Site fixing of shear connectors
Site fixing of shear connectors shall comply with the following:
(a)
The thickness of the steel flange shall satisfy the requirements of Clause 8.4.3.1.
(b)
The distance between the edge of a shear connector, and either the end or the side of
an adjacent steel rib of an open-rib profile, shall be not less than as shown in
Figure 8.4.2.
NOTE: For closed-rib profiles see Note to Clause 8.4.1(d).
(c)
The surface of the parent material, in the areas to which the shear connectors are to be
welded, shall be free of scale, rust, moisture, paint, mud, sand, grease or other
injurious material to the extent necessary to obtain satisfactory welds. The suitability
of the surface conditions for stud welding shall be assessed in accordance with the
requirements of AS 1554.2.
NOTE: A thin film of manganese zinc silicate paint may be acceptable.
(d)
Automatic stud welding procedures through profiled steel sheeting shall be in
accordance with AS 1554.2. Studs shall not be welded through longitudinal stiffeners
and ceramic ferrules shall not come into contact with the stiffeners or sheeting ribs
during the welding operation.
(e)
The different types of shear connectors shall be attached in accordance with
Clause 8.4.3. In particular, their proximity to profiled steel sheeting shall be in
accordance with Clause 8.4.
11.4 FORMWORK AND FALSEWORK
11.4.1 General
The arrangement of falsework shall take account of the deflections of the steel beams
during concreting to prevent undue distortion of the slab soffit.
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AS 2327.1—2003
Removal of slab formwork/falsework and props to beams shall not commence until the
concrete has attained a characteristic compressive strength f′ cj of 15 MPa, i.e., end of
Construction Stage 4 (see Clause 4.2). The minimum period of time before stripping forms
or removing props shall be not less than that given in the project drawings or specification.
All dirt, excess water, ceramic ferrules and other deleterious matter accumulated during
construction shall be removed from the top surface of the formwork prior to concrete
placement. Oil shall not come into contact with the surface of profiled steel sheeting.
11.4.2 Solid slabs
Formwork and falsework for solid slabs shall comply with AS 3610.
11.4.3 Composite slabs
The manufacturer’s recommendations regarding the installation of profiled steel sheeting
shall be followed. The maximum deflection of the sheeting while it supports the plastic
concrete shall not exceed the value assumed in design.
NOTE: Suggested limits are given in Appendix C, Paragraph C2.
11.5 REINFORCEMENT
Reinforcement shall be supplied and fixed in accordance with AS 3600.
NOTE: When fabricating and placing the transverse reinforcement, special attention should be
given to the detailing requirements of Clause 9.7.1.
11.6 CONCRETE
11.6.1 Materials, manufacture and delivery
Concrete materials, manufacture and delivery shall be in accordance with AS 1379
including quality assessment for concrete as supplied.
11.6.2 Concrete after delivery
Handling, placing, compacting, curing and protection of plastic concrete after delivery shall
be in accordance with AS 3600, including determination of in situ strength at various stages
of construction.
11.7 FIRE PROTECTION MATERIAL
Sprayed mineral coatings shall be applied to the members in accordance with AS 3784.1.
Other fire protection materials shall be installed in accordance with the manufacturer’s
recommendations.
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AS 2327.1—2003
78
SECT ION
12
LO AD
TES T I NG
12.1 GENERAL
12.1.1 Purpose of testing
Beams designed by calculation in accordance with other parts of this Standard are not
required to be tested. Tests may be accepted as an alternative to calculation, or may become
necessary in special circumstances, in order to satisfy the requirements of Clause 3.3.1 with
respect to strength and Clause 3.3.2 with respect to deflection.
Beams may be either—
(a)
proof tested in accordance with Clause 12.2 to ascertain the structural characteristics
of an existing structure, substructure or individual member; or
(b)
prototype tested in accordance with Clause 12.3, to ascertain the structural
characteristics of a particular class of beams which are nominally identical to the
beams tested.
12.1.2 Test set-up
All measuring equipment shall be calibrated and chosen to suit the range of measurements
anticipated in order to obtain accurate results. Care shall be exercised to ensure that no
artificial restraints are applied to a test specimen. All necessary precautions shall be taken
to prevent the collapse of any part of a structure being proof tested.
NOTE: In the case of prototype testing, it is suggested that if the details of the end connections
are also known, then the beams should also be tested with their connections.
12.1.3 Test load
The test load shall simulate the design loads for the relevant limit states. The test load shall
be applied gradually at a rate as uniform as practicable and without impact. The distribution
and duration of forces applied in the test shall represent those forces to which the structure
is deemed to be subjected under the requirements of Section 4.
12.1.4 Test deflections
The maximum vertical deflections of the beam shall be measured with respect to an
appropriate datum. Deflections shall, as a minimum requirement, be recorded at the
following times:
(a)
During the application of the test load.
(b)
Immediately the full test load has been applied.
(c)
Immediately prior to removing the test load.
(d)
After the removal of the test load.
12.2 PROOF TESTING
12.2.1 Test procedures
A proof test shall be conducted according to the following procedures:
(a)
Before applying any load, record the original position of the members involved.
(b)
Apply the test load for the relevant limit state, as determined from Clause 4.1.4.
(c)
Maintain the test load for the necessary period.
(d)
Remove the test load.
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AS 2327.1—2003
12.2.2 Criteria for acceptance
Criteria for acceptance shall be as follows:
(a)
Acceptance for strength The test structure, substructure or beam shall be deemed to
comply with the requirements for strength if it is able to sustain the strength limit
state test load for at least 24 h without incurring any significant damage.
(b)
Acceptance for deflection The maximum deflection of any beam under the
serviceability limit state test load shall be within the serviceability limits appropriate
to the structure.
12.2.3 Damage incurred during test
The tested members and their end connections shall be regularly inspected to determine the
nature and extent of any damage incurred during the test. The effects of the damage shall be
considered and the test disbanded if collapse seems likely. At the completion of the test,
appropriate repairs to damaged parts shall be carried out.
12.3 PROTOTYPE TESTING
12.3.1 Construction of prototypes
The prototype beams shall be constructed from materials that comply with Section 2. Any
additional requirements of a manufacturing specification shall also be complied with.
12.3.2 Number of prototypes
The number of prototypes to be tested should be selected so that statistically reliable
estimates for the strength or deflection, or both, of the design member can be determined
from the results of the tests, but in any case not fewer than two prototypes shall be tested.
12.3.3 Test loads
The test loads shall be adjusted so that the total load on each prototype is equal to the
design load for the relevant limit state as determined from Clause 4.1.4, multiplied by the
appropriate factor given in Table 12.1, corresponding to the number of prototypes to be
tested, unless a reliability analysis shows that a smaller value of the factor can be adopted.
TABLE 12.1
FACTORS TO ALLOW FOR
VARIABILITY OF STRUCTURAL UNITS
Number of similar
units to be tested
Strength
limit state
Serviceability
limit state
2
1.4
1.2
3
1.3
1.2
4
1.3
1.1
5 to 9
1.3
1.1
10 or more
1.2
1.1
12.3.4 Test procedure
The method of applying the test load to a prototype beam shall reflect the most adverse
conditions expected to apply during the in-service condition.
A prototype test shall be conducted according to the following procedure:
(a)
Before applying any load, record the original position of the beam.
(b)
Apply the test load for the relevant limit state as determined from Clause 12.1.3.
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(c)
Maintain the test load for the necessary period.
(d)
Remove the test load.
12.3.5 Criteria for acceptance
The group of beams represented by the prototypes shall be deemed to comply with the
requirements of this Standard for serviceability and strength if both of the following
requirements are satisfied:
(a)
Acceptance for strength The test beam shall be deemed to comply with the
requirements for strength if it is able to sustain the strength limit state test load for at
least 5 minutes without incurring any significant damage.
(b)
Acceptance for serviceability The maximum deflection of any beam under the
serviceability limit state test load shall be within the serviceability deflection limits
appropriate to the structure.
12.3.6 Acceptance of manufactured beams
Manufactured beams shall be similar in all respects to the beams tested.
12.4 TEST REPORTS
A report shall be prepared, which shall contain, in addition to the test load and deflection
records, a clear description of the test set-up, including the methods of supporting and
loading the members as appropriate, the method of measuring deflections and any other
relevant data. The report shall also contain a statement as to whether or not the structure,
substructure or members tested satisfied the relevant acceptance criteria in Clauses 12.2.2
or 12.3.6 as appropriate.
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AS 2327.1—2003
APPENDIX A
LIST OF REFERENCED DOCUMENTS
(Normative)
The following documents are referred to in this Standard:
AS
1110
ISO metric hexagon precision bolts and screws (all parts)
1111
ISO metric hexagon commercial bolts and screws (all parts)
1112
ISO metric hexagon nuts, including thin nuts, slotted nuts and castle nuts (all
parts)
1163
Structural steel hollow sections
1170
1170.4
Minimum design loads on structures
Part 4: Earthquake loads
1275
Metric screw threads for fasteners
1379
Specification and supply of concrete
1397
Steel sheet and strip—Hot-dipped zinc-coated or aluminium/zinc-coated
1530
1530.4
Methods for fire tests on building materials, components and structures
Part 4: Fire-resistance test of elements of building construction
1554
1554.2
Structural steel welding
Part 2: Stud welding (steel studs to steel)
3600
Concrete structures
3610
Formwork for concrete
3610Supp 2 Formwork for concrete—Commentary
3784
3784.1
Coatings for fire protection of building elements
Part 1: Guide to selection and installation of sprayed mineral coatings
4100
Steel structures
AS/NZS
1170
1170.0
1170.1
1170.2
1170.3
Structural design actions
Part 0: General principles
Part 1: Permanent, imposed and other actions
Part 2: Wind actions
Part 3: Snow and ice actions
NOTE: At the time of publishing the Building Code of Australia (BCA) references the
AS 1170.3—1990 edition
1252
High-strength steel bolts with associated nuts and washers for structural
engineering
1365
Tolerances for flat-rolled steel products
1554
1554.1
1554.4
Structural steel welding
Part 1: Welding of steel structures
Part 4: Welding of high-strength quenched and tempered steels
1594
Hot-rolled steel flat products
3678
Structural steel—Hot-rolled plates, floorplates and slabs
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3679
3679.1
3679.2
Structural steel
Part 1: Hot-rolled bars and sections
Part 2: Welded I-sections
4671
Steel reinforcing materials
HB 77
Australian Bridge Design Code
BS
5950
5950-3
 Standards Australia
Structural use of steelwork in building
Part 3: Design in composite construction. Code of practice for design of
simple and continuous composite beams
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AS 2327.1—2003
APPENDIX B
CALCULATION OF DEFLECTIONS BY SIMPLIFIED METHOD
(Normative)
B1 DESIGN PROCEDURE
Design for deflection in accordance with the simplified method defined in Clause 7.2.4
shall be performed as follows (see Figure B1):
(a)
Determine which of the deflection components defined in Paragraph B2 are relevant
to the design, and calculate the corresponding serviceability design loads.
(b)
Identify the different cross-sections along the steel beam during Construction
Stages 1 to 3, and along the composite beam during Construction Stages 5 and 6 and
the in-service condition. Calculate their elastic section properties, which in the case
of the composite beam shall initially be performed assuming full interaction in
accordance with Paragraph B3.
(c)
Calculate the maximum stress (f max ) that occurs in the steel beam during Construction
Stages 1 to 6 and the in-service condition in accordance with Paragraph B4, and
check that it does not exceed 0.9 f yb in magnitude.
(d)
Identify the maximum moment cross-section of the composite beam during the inservice condition and calculate the degree of shear connection β m at this cross-section
in accordance with Section 6 (see Note 1).
(e)
Calculate the effective second moment of areas Ieti and Iet l of the different composite
beam cross-sections identified in Step (b) accounting for the degree of shear
connection β m calculated at Step (d), in accordance with Paragraph B3.4.
(f)
Calculate the magnitude of the relevant deflection components assuming linear-elastic
behaviour, accounting for changes in cross-section along the length of the beam and
the magnitude and distribution of applied loads.
(g)
Calculate the corresponding values of the total and incremental deflections according
to the following equations as appropriate:
(i)
Total deflection measured from slab top face:
δ tot = δ C5.6 + δ Ii + δ Il + δ Ish
(ii)
. . . B1(1)
Total deflection measured from steel beam soffit (see Note 2):
δ tot = δ C1.3 + δ C5.6 + δ Ii + δ Il + δ Ish − precamber
. . . B1(2)
(iii) Incremental deflection calculated assuming formwork/falsework or props
removed before installation of brittle finishes (see Note 3):
δ inc = δ Ii + δ Il + 0.6 δ Ish
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. . . B1(3)
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AS 2327.1—2003
(h)
84
Check that the limits chosen for the total and incremental deflections are not
exceeded.
NOTES:
1
If the maximum moment occurs at more than one cross-section, then the degree of shear
connection β m is calculated as the maximum degree of shear connection that occurs for
any of these cross-sections.
2
Advice on limits for cambering steel beams is given in Reference 8, Appendix I.
3
In the derivation of this equation it is assumed that 40% of the shrinkage deflection δ Ish
occurs before the attachment of brittle elements. A different allowance may be made by
adjusting the value of the coefficient of δ Ish.
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AS 2327.1—2003
FIGURE B1 FLOW CHART SHOWING SIMPLIFIED METHOD OF DEFLECTION DESIGN
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B2 DEFLECTION COMPONENTS AND CORRESPONDING DESIGN LOADS
Design loads shall be determined for the serviceability limit state. The loads may be
concentrated or distributed, acting directly on the steel or composite beam, or may be
concentrated loads on the steel beam resulting from attached members.
The components of deflection to be considered in the incremental and total deflection, and
the corresponding design loads, shall be determined from the following as appropriate:
(a)
Immediate deflection of steel beam during Construction Stages 1 to 3 (δC1.3).
Deflections arising from the weight of the steel beam, formwork (permanent or
removable), concrete and reinforcement (i.e., dead loads G C1.3).
(b)
Immediate deflection of composite beam during Construction Stages 5 and 6 (δC5.6).
Deflections arising from removal of formwork/falsework supporting dead loads
(GC1.3), and from the addition of any superimposed dead loads (Gsup) (see Note 1).
(c)
Immediate deflection of composite beam during in-service condition (δIi). Deflection
arising from the short-term component of the live load (ψs Q).
(d)
Long-term creep deflection of composite beam during in-service condition (δI l).
Creep deflections arising from the dead loads Gsup , and the long-term component of
the live load (ψ l Q) (see Note 2) and, for propped construction only, GCl.3 .
(e)
Long-term shrinkage deflection of the composite beam during the in-service condition
( δIsh ). Deflections arising from shrinkage of the concrete (see Note 3).
NOTES:
1
The resultant forces that act on the composite beam as a result of removing the falsework
or props are affected by the formwork/falsework or propping arrangement.
2
The long-term deflection calculated directly using the long-term section property includes
the contribution from the immediate deflection. Therefore, the component δ I l has to be
calculated by subtracting the combined immediate deflection due to the loads Gsup and
ψ l Q and, if propped, GC1.3 from the long-term deflection calculated using these same
loads.
3
An acceptable method for calculating the deflection is given in Reference 8, Appendix I.
B3 ELASTIC SECTION PROPERTIES OF COMPOSITE
SECTIONS ASSUMING FULL INTERACTION
BEAM
CROSS-
B3.1 General
The elastic section properties of a composite beam cross-section, assuming full interaction
between the steel beam and concrete slab (see Figure B3.1), shall be calculated taking into
account the position of the elastic neutral axis within the depth of the member in
accordance with Paragraphs B3.2 and B3.3, ignoring the tensile strength of the concrete.
The properties shall be calculated using the effective section determined in accordance with
Clause 5.2 assuming complete shear connection, i.e., β = 1. The modular ratio α shall be
taken as Es/E c for the calculation of steel stresses or immediate deflection components using
I ti , and 3E s/Ec for the calculation of long-term deflection components using I t l , where the
modulus of elasticity of concrete E c shall be determined in accordance with AS 3600 taking
into account the mean value of the compressive strength of the concrete at the relevant age.
The modulus of elasticity of the steel beam Es shall be taken as equal to 200 × 103 MPa. In
composite slabs, the width of concrete between the sheeting ribs measured perpendicular to
the longitudinal axis of the steel beam is calculated using the factor λ determined from
Clause 5.2.2.2.
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AS 2327.1—2003
FIGURE B3.1 GEOMETRY OF COMPOSITE BEAM AS AN EQUIVALENT STEEL
SECTION FOR CALCULATION OF ELASTIC SECTION PROPERTIES
B3.2 Elastic neutral axis in concrete slab
When the elastic neutral axis is located in the concrete slab, calculations shall be as
follows:
(a)
Solid slab (i.e., kD b ≤ D c):
kDb =
It =
d sg
2
[ αc (αc + 4) − αc ]
1
1
. . . B3.2(1)
1
bcf (kDb )3
+ I s + As (dsg − kDb ) 2
3α
. . . B3.2(2)
where
kD b = depth of elastic neutral axis below top surface of slab
It
= second moment of area of transformed section with respect to steel
c1
=
2 As
bcf d sg
NOTE: Iti = I t using α = E s /E c and I tl = I t using α = 3Es /E c
(b)
Composite slab with λ = 0:
(i)
Neutral axis in cover slab (i.e., kD b ≤ (D c − h r))
kDb =
d sg
2
[ αc (αc + 4) − αc ]
1
1
1
b (kDb )
2
I t = cf
+ I s + As (d sg − kDb )
3α
. . . B3.2(3)
3
(ii)
. . . B3.2(4)
Neutral axis in concrete between sheeting ribs (i.e. (Dc − h r) < kD b ≤ Dc)

 b
b
2
kDb =  cf (Dc − hr ) + As d sg  /  cf (Dc − hr ) + As 
2
α
α

 

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. . . B3.2(5)
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I t = I s + As (d sg − kDb ) +
2
bcf (Dc − hr ) bcf (Dc − hr )
(2kDb − Dc + hr )2
+
12α
4α
3
. . . B3.2(6)
(c)
Composite slab with λ > 0:
(i)
Neutral axis in cover slab (i.e., kD b ≤ (D c − h r))
kDb =
d sg
2
[ αc (αc + 4) − αc ]
1
1
. . . B3.2(7)
1
. . . B3.2(8)
b (kDb )
2
I t = cf
+ I s + As (d sg − kDb )
3α
3
(ii)
Neutral axis in concrete between sheeting ribs (i.e., (D c − hr ) < kD b ≤ D c)
0.5




dsg αc1  αc1
2
c
2
(
D
h
α
αc1
−

1
c
r 


kDb =
+ 4  + c2 c2 +
+
−
− c2  ..B3.2(9)





2  λ  λ
d
λ
λ

sg




It =
3
b (D − hr )
λbcf (kDb − Dc + hr )3
2
+ I s + As (d sg − kDb ) + cf c
3α
12α
. . . B3.2(10)
 b (D − hr ) 
2
+  cf c
(2 kDb − Dc + hr )
4α


where
c2 =
2(1 − λ )
(Dc − hr )
d sg λ
B3.3 Elastic neutral axis in steel beam
When the elastic neutral axis is located in the steel beam (i.e., kD b > Dc), calculations shall
be as follows:
(a)
Solid slab:
 b D2
 b D

kDb =  cf c + As dsg  / cf c + As 

 2α
  α
I t = I s + As (d sg − kDb ) +
2
(b)
bcf Dc3 bcf Dc
+
(2kDb − Dc )2
12α
4α
Composite slab with λ ≥ 0:
b
kDb =  cf
 2α
{ (D
c
. . . B3.3(1)
. . . B3.3(2)
}

2
− hr ) + λ hr (2 Dc + hr ) + As d sg  /

. . . B3.3(3)

 bcf
 α (Dc − hr + λ hr ) + As 
I t = I s + As (d sg − kDb )
2
b (D − h ) b (D − hr )
+ cf c r + cf c
(2kDb − Dc + hr )2
12α
4α
3
λbcf hr3 λbcf hr 
h 
+
+
 kDb − Dc + r 
12α
α 
2
 Standards Australia
2
. . . B3.3(4)
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AS 2327.1—2003
B3.4 Effective second moments of area of composite beam
For composite beams with partial shear connection at the cross-section under maximum
bending (i.e., β m < 1), the effective second moments of area (Ieti and Iet l) shall be calculated
as follows:
Ieti
=
I ti + 0.6 (1 − β m) (Is − I ti )
. . . B3.4(1)
Iet l
=
I t l + 0.6 (1 − β m) (Is − I t l)
. . . B3.4(2)
where
I ti and I t l are calculated in accordance with Paragraph B3.1.
B4 MAXIMUM STRESS IN STEEL BEAM
The maximum tensile or compressive stress that occurs in the steel beam during
Construction Stages 1 to 6 and during the in-service condition, shall be calculated taking
into account the support conditions of the steel or composite beam, the magnitude and
distribution of the applied loads, and the stage at which composite action is developed.
Maximum stresses shall be calculated in accordance with the following:
(a)
Construction Stages 1 to 3 Prior to the development of composite action, the
maximum stress in the steel beam shall be calculated using the load combination
G + Q considering Construction Stages 1 to 3 separately. The values of nominal dead
and live loads G and Q defined in Clause 4.2 appropriate to each construction stage
shall be used.
The section moduli of the steel beam Zst and Zsb corresponding to the extreme top and
bottom fibres of the steel beam shall be calculated as Is/ds and Is/(Ds − ds),
respectively, where d s is the depth of the elastic neutral axis of the steel beam below
the top of the beam.
(b)
Construction Stages 5 to 6 Following the development of composite action, the
maximum stress in the steel beam shall be calculated taking into account the initial
stress in the beam locked in when the concrete sets, and the additional stress that
results when the composite beam is subsequently loaded, ignoring the effects of
concrete creep and shrinkage.
The section moduli of the composite beam Z ct and Z cb corresponding to the extreme
top and bottom fibres of the steel beam shall be calculated, assuming full interaction,
as I ti /(Db − kDb − Ds) and I ti/(D b − kD b) respectively, where kD b and I ti are calculated
in accordance with Paragraph B3. At cross-sections where the steel stresses are being
calculated and β < 0.4, composite action shall be ignored and the section moduli of
the steel beam alone shall be used.
The stresses in the steel beam immediately prior to initial set of the concrete shall be
calculated assuming the beam supports the permanent dead load GC1.3 defined in
Paragraph B2. The load on the composite beam shall be calculated using the load
combination Gsup + Q, where Gsup equals the superimposed dead load applied during
Construction Stages 5 and 6, and Q equals the value of nominal live load defined in
Paragraph F2.6, Appendix F appropriate to each of these construction stages.
(c)
In-service condition During the in-service condition, the additional stresses that
arise from live load Q acting on the composite beam shall be calculated using ψs Q.
The section moduli of the composite beam Z ct and Z cb corresponding to the extreme
top and bottom fibres of the steel beam shall be calculated, assuming full interaction,
as I ti (D b − kDb − Ds) and Iti /(D b − kD b) respectively, where kDb and Iti shall be
calculated in accordance with Paragraph B3. At cross-sections where the steel stresses
are being calculated and β < 0.4, composite action shall be ignored and the section
moduli of the steel beam alone shall be used.
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90
APPENDIX C
SUGGESTED LIMITS FOR CALCULATED DEFLECTIONS
(Informative)
C1 BEAMS
The deflection limit chosen should not exceed the relevant value given in Table C1 unless it
can be shown that exceeding these values will not impair the serviceability of the member.
TABLE C1
SUGGESTED LIMITS FOR CALCULATED DEFLECTION OF BEAMS
Type of member
Deflection to be
considered
All members
The total deflection
Members
supporting brittle
elements
The incremental
deflection that occurs after
the addition or attachment
of the elements
Deflection limitation
(∆
∆ /Lef ) for span (see
Note 1)
Deflection limitation
(∆
∆ /Lef ) for cantilevers
(see Note 2)
1/250
1/125
1/500 where provision
is made to minimize the
effect of movement,
otherwise 1/1000
1/250 where provision is
made to minimize the
effect of movement,
otherwise 1/500
NOTES:
1
Deflection limits given may not safeguard against ponding of water.
2
For cantilevers, the values of ∆/Lef given in this Table apply only if the rotation at the support is
included in the calculation of ∆.
C2 PROFILED STEEL SHEETING
The vertical deflection of the sheeting under its own weight plus the weight of plastic
concrete and reinforcement, but excluding the construction loads, should not exceed the
lesser of 30 mm or—
(a)
L ef /240 where visual quality and general alignment of the slab soffit is considered
important, or the deflection of the soffit affects the application of finishes or the
installation of building services; or
(b)
L ef /130 in other cases,
where Lef is the effective span between supports (props being supports in this context), which
can be calculated from Figure H1(a) by substituting h r for Ds, irrespective of whether or not
the sheeting is continuous past the support.
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APPENDIX D
CALCULATION OF DESIGN MOMENT CAPACITY ( φMbv) AS A FUNCTION OF
DEGREE OF SHEAR CONNECTION (β )
(Normative)
D1 GENERAL
In accordance with Clause 6.4, the design moment capacity (φMbv ) shall be calculated as a
function of the degree of shear connection β from—
(a)
Paragraph D2 if γ ≤ 0.5; or
(b)
Paragraph D3 if 0.5 < γ ≤ 1.
NOTE: The steel section has been modelled on a mono-symmetric I-section. For other types of
steel sections, the same equations can be used noting that—
(a)
for sections with multiple webs, the I-section web thickness should be taken as the sum of
the effective thicknesses of the webs; and
(b)
for sections without a bottom flange, the bottom flange area (Af2) should be taken as zero.
D2 CROSS-SECTIONS WHERE γ ≤ 0.5
D2.1 General
At beam cross-sections where γ ≤ 0.5, the design moment capacity φM bv shall be assumed to
be independent of the shear ratio γ and in this case equals φMb .
D2.2 Calculation of φM b as a function of β
The design moment capacity φM b may be calculated as a continuous function of β as shown
in Figure D2.2(a) by using the equations based on rectangular stress block theory given in
Paragraph D2.3.
Alternatively, a bilinear approximation to the continuous function shown in Figure D2.2(a)
may be used to calculate the relationship between φMb and β . This requires the design
moment capacities φMs , φM bc and φM b.5 (i.e., φM b when β = 0.5) to be calculated from
Paragraph D2.3. Linear interpolation shall be used to calculate φM b between these points as
follows (see Figure D2.2(b)):
(a)
0 < β ≤ 0.5
φM b = (1 − 2 β )φM s + 2 βφM b.5
(b)
. . . D2.2(1)
0.5 < β < 1.0
φM b = ( 2 β − 1)φM bc − 2( β − 1)φM b.5
. . . D2.2(2)
D2.3 Nominal moment capacities M bc and M b for γ ≤ 0.5
D2.3.1 General
At beam cross-sections where γ ≤ 0.5—
(a)
the nominal moment capacity M bc corresponding to complete shear connection,
(i.e., β = 1.0) shall be determined in accordance with Paragraph D2.3.2; and
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92
the nominal moment capacity M b corresponding to partial shear connection,
(i.e., β < 1.0) shall be determined in accordance with Paragraph D2.3.3.
NOTE: The equations for M bc and M b given in Paragraphs D2.3.2 and D2.3.3 have been derived
using rectangular stress block theory based on the following assumptions and calculation
principles:
(a)
In accordance with Section 5, the effective section of the composite beam cross-section
comprises an effective width of the concrete compression flange bcf (which takes account of
the effects of in-plane shear flexibility, i.e., shear-lag) and an effective portion of the steel
beam (such that all its compression plate elements are compact).
(b)
The concrete has zero tensile strength.
(c)
The presence of any longitudinal reinforcement in the slab is ignored.
FIGURE D2.2 DESIGN MOMENT CAPACITY φ M b AS A FUNCTION OF β WHEN γ ≤ 0.5
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(d)
Any profiled steel sheeting does not support either longitudinal tensile or compressive forces
in the spanning direction of the beam.
(e)
A uniform compressive stress of 0.85f ′ c develops in the concrete over the slab effective width
directly below the top surface of the slab.
(f)
The orientation of the sheeting ribs with respect to the longitudinal axis of the steel beam
affects the transfer of longitudinal compressive forces in the concrete between the sheeting
ribs (see Paragraph D2.3.2).
(g)
The compressive force in the concrete cannot exceed the longitudinal shear force, which can
be transferred by the shear connection between the steel beam and the concrete slab at the
strength limit state.
(h)
The part of the effective portion of the steel beam in tension is stressed uniformly to the yield
stress of either the flanges (fyf) or webs (f yw) as appropriate.
(i)
Any part of the steel beam in compression is stressed uniformly to the yield stress of either the
flanges (f yf) or webs (fyw) as appropriate, and the strain gradient across the plastic neutral axis
is infinite, i.e., strain-compatibility is ignored.
(j)
The resultant tensile force in the steel beam equals the compressive force in the concrete slab
and, therefore, the force in the concrete cannot exceed the tensile capacity of the steel beam.
D2.3.2 Nominal moment capacity Mbc (β = 1.0)
The nominal moment capacity at a cross-section of a composite beam with complete shear
connection (M bc) shall be determined in accordance with the procedure below, referring to
Figure D2.3.2 for notation. It should be noted that the equations for the unusual case when
the compressive stress zone falls within the bottom flange of the steel beam have not been
formulated.
(a)
Calculate—
F st = (A f1 + A f2) f yf + Aw f yw; and
(i)
. . . D2.3.2(1)
(ii)
d sr
where
F st = tensile force in steel beam, assuming that the entire cross-sectional area
is yielded in tension
d sr = depth at which Fst acts below the top surface of the slab, noting that dsr
equals dsg unless the section is monosymmetric and f yf does not equal
f yw
(b)
Calculate the following compressive forces:
= 0.85 f c′bcf ( Dc − hr )
Fc1
. . . D2.3.2(2)
Fc2
=
0.85 f c′λbcf hr
. . . D2.3.2(3)
Fscf
=
f yf bsf 1tfl
. . . D2.3.2(4)
F c1
=
longitudinal compressive capacity of concrete cover slab within slab
effective width
F c2
=
longitudinal compressive capacity of concrete between steel ribs
within slab effective width
F scf
=
compressive capacity of top flange of steel beam
λ
=
as defined in Clause 5.2.2.2
where
NOTES:
1
h r = 0 for solid slabs.
2
F c2 = 0 if steel sheeting ribs are perpendicular to steel beam, i.e., θ = 90°.
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FIGURE D2.3.2 NOTATION FOR M bc DETERMINATION
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(c)
AS 2327.1—2003
Calculate dc , d h , Fcc and finally M bc from the appropriate case of those that follow
defined by the bounds on F st:
(i)
Case 1 Fst ≤ Fc1
If Fst ≤ Fc1 , then d h ≤ (Dc − h r); and
dc =
d h = (D c − h r) F cc/Fc1
. . . D2.3.2(5)
F cc = F st
M bc =
(ii)
Fcc (d sr − dc/2)
. . . D2.3.2(6)
Case 2 Fc1 < Fst ≤ (Fc1 + Fc2)
If Fc1 < Fst ≤ (Fc1 + F c2), then (Dc − h r) < d h ≤ Dc; and
dc =
d h = (D c − h r) + [h r(F st − F c1)/Fc2]
F cc =
Fst
M bc = F c1[dsr − (D c − h r)/2]+(Fcc − F c1)[dsr − d h/2 − (D c − h r)/2]
. . . D2.3.2(7)
. . . D2.3.2(8)
(iii) Case 3 (Fc1 + Fc2) < Fst ≤ (Fc1 + F c2 + 2F scf )
If (Fc1 + Fc2) < Fst ≤ (F c1 + F c2 + 2Fscf ), then D c < dh ≤ (Dc + t f1); and
(iv)
dc =
Dc
F cc =
F c1 + Fc2; Fsc = Fst − F cc
dh =
D c + t f1 Fsc/(2Fscf )
. . . D2.3.2(10)
M bc =
F c1 [d s − (Dc − h r)/2] + F c2 (d sr − Dc + h r/2)
+ Fsc [dsr − (D c + d h )/2]
. . . D2.3.2(11)
. . . D2.3.2(9)
Case 4 (Fc1 + Fc2 + 2F scf ) < Fst
If (Fc1 + Fc2 + 2Fscf ) < Fst, then (D c + t f1) < d h ≤ d sr; and
dc =
Dc
F cc =
F c1 + Fc2
Calculate compressive force component in steel beam web(s) Fb:
Fb =
F st − Fcc − 2Fscf
. . . D2.3.2(12)
dh =
D c + t f1 + F b/(2f ywt w)
. . . D2.3.2(13)
M bc =
F c1 [d sr − (Dc − h r)/2] + Fc2 (dsr − Dc + h r/2)
+ 2F scf (dsr − Dc − t f1/2) + F b[dsr − (Dc + t f1 + d h )/2]
. . . D2.3.2(14)
D2.4 Nominal moment capacity M b (0 < β < 1.0)
The nominal moment capacity of a cross-section of a composite beam with partial shear
connection (M b) shall be determined in accordance with the following procedure, referring to
Figure D2.3.3 for notation:
(a)
Calculate Fst and dsr from Paragraph D2.3.2(a).
(b)
Calculate Fc1, Fc2 and Fscf from Paragraph D2.3.2(b).
(c)
Calculate Fcc from Paragraph D2.3.2(c) for the applicable case corresponding to
complete shear connection.
(d)
Calculate Fcp from either—
(i)
when the strength of the shear connection is known—
F cp = n i f ds
. . . D2.3.3(1)
< F cc (otherwise the cross-section has complete shear connection); or
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96
when the degree of shear connection β (< 1.0) is specified—
F cp = β Fcc
(e)
Calculate—
F sc = F st − Fcp
(f)
. . . D2.3.3(3)
Calculate d c from one of the following as appropriate:
(i)
If Fcp ≤ F c1 , then dc ≤ (D c − h r); and
dc
(ii)
= (Dc − h r) Fcp/Fc1
. . . D2.3.3(4)
If Fcp > Fc1, then (D c − h r) < d c ≤ D c; and
dc
(g)
. . . D2.3.3(2)
= D c − h r + h r (F cp − Fc1)/Fc2
. . . D2.3.3(5)
Calculate d h from one of the following as appropriate:
(i)
If Fsc ≤ 2Fscf , then D c < d h ≤ (D c + t f1); and
dh
(ii)
= D c + t f1 Fsc/(2Fscf )
. . . D2.3.3(6)
If 2F scf < F sc ≤ 2F scf + 2Fscw, then (Dc + t f1 ) < d h ≤ (D c + Ds − t f2); and
dh
= D c + t f1 + (Fsc − 2F scf )/(2 fyw tw)
. . . D2.3.3(7)
where
F scw = f yw d 1 t w
(iii) If Fsc > 2F scf + 2Fscw, then (D c + Ds − t f2 ) < d h ≤ (D c + D s), and
dh
(h)
= D c + Ds − t f2 + (Fsc − 2Fscf − 2Fscw)/(2 f yf bsf2 )
. . . D2.3.3(8)
Calculate Mb from the appropriate case following defined by the bounds on F cp and Fsc,
using the relevant values of d c and d h from (f) and (g), respectively:
(i)
Case 1 Fcp ≤ F c1 and F sc ≤ 2Fscf
If Fcp ≤ F c1 and F sc ≤ 2Fscf , then
M b = F cp (d sr − d c/2) + Fsc [dsr − (D c + d h )/2]
. . . D2.3.3(9)
where
d c is obtained from Equation D2.3.3(4); and
d h is obtained from Equation D2.3.3(6)
(ii)
Case 2 Fcp ≤ F c1 and 2Fscf < Fsc ≤ (2Fscf + 2F scw)
If Fcp ≤ F c1 and 2Fscf < Fsc ≤ (2Fscf + 2Fscw), then
M b = F cp (d sr − d c/2) + 2Fscf (d sr − D c − t f1 /2)
+ (Fsc − 2Fscf )[dsr − (Dc + t f1 + d h )/2]
. . . D2.3.3(10)
where
d c is obtained from Equation 2.3.3(4); and
d h is obtained from Equation 2.3.3(7).
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FIGURE D2.3.3 (in part) NOTATION FOR M b DETERMINATION
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(iii) Case 3 Fcp ≤ F c1 and F sc > (2F scf + 2Fscw)
If Fcp ≤ F c1 and F sc > (2Fscf + 2Fscw), then
M b = F cp (d sr − d c/2) + 2Fscf (d sr − D c − t f1 /2)
+ 2F scw [dsr − Dc − (D s + t f1 − t f2 )/2]
+ F b [dsr − (Dc + Ds − t f2 + d h)/2]
. . . D2.3.3(11)
where
d c is obtained from Equation D2.3.3(4);
d h is obtained from Equation D2.3.3(8); and
F b = Fsc − 2Fscf − 2Fscw
(iv)
Case 4 Fcp > Fc1 and Fsc ≤ 2Fscf
If Fcp > Fc1 and Fsc ≤ 2Fscf, then
M b = F c1 [d sr − (Dc − h r)/2] + (Fcp − Fc1)[d sr −(D c − h r + d c)/2]
+ Fsc [dsr − (Dc + d h )/2]
. . . D2.3.3(12)
where
d c is obtained from Equation D2.3.3(5); and
d h is obtained from Equation D2.3.3(6).
(v)
Case 5 Fcp > Fc1 and 2Fscf < Fsc ≤ (2Fscf + 2F scw)
If Fcp > Fc1 and 2Fscf < Fsc ≤ (2Fscf + 2F scw), then
M b = F c1[dsr − (D c − h r)/2] + (Fcp − Fc1)[dsr − (Dc − h r + dc)/2]
+ 2F scf (d sr − Dc − t f1/2) + (Fsc − 2Fscf )[dsr − (Dc + t f1 + d h )/2]
. . . D2.3.3(13)
where
d c is obtained from Equation D2.3.3(5); and
d h is obtained from Equation D2.3.3(7).
(vi)
Case 6 Fcp > Fc1 and Fsc > (2F scf + 2Fscw)
If Fcp > Fc1 and Fsc > (2F scf + 2Fscw), then
M b = F c1 [d sr − (Dc − h r)/2] + (Fcp − F cl) [dsr − (Dc − h r + dc)/2]
+ 2F scf (dsr − D c − t f1 /2) + 2Fscw[d sr − Dc − (Ds + t f1 − t f2 )/2]
. . . D2.3.3(14)
+ F b [dsr − (Dc + Ds − t f2 + d h)/2]
where
d c is obtained from Equation D2.3.3(5);
d h is obtained from Equation D2.3.3(8); and
F b = F sc − 2Fscf − 2Fscw
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FIGURE D2.3.3 (in part) NOTATION FOR M b DETERMINATION
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D3 CROSS-SECTIONS WHERE 0.5 < γ ≤ 1
D3.1 General
At beam cross-sections where 0.5 < γ ≤ 1.0, the design moment capacity φM bv shall be
assumed to be dependent on the shear ratio γ according to the appropriate relationship
defined in Paragraph D3.2, as well as the degree of shear connection β .
D3.2 Relationship with γ
For a particular value of β < 1.0, it shall be assumed that φM bv reduces linearly from φMb
when γ = 0.5 to φM bf when γ = 1.0 (i.e., φM bf is the design moment capacity with the concrete
slab and steel beam flanges only, and both φM b and φM bf shall be calculated in accordance
with Paragraph D3.3) (see Figure D3.2), i.e.
φM bv = φM b − ( φMb − φM bf ) (2 γ − 1)
. . . D3.2(1)
Similarly, for β = 1.0 it shall be assumed that φM bv reduces linearly from φM bc when γ = 0.5
to φMbfc when γ = 1.0, where M bc and M bfc shall be calculated in accordance with
Paragraphs D2.3.2 and D3.4.2 respectively (see Figure D3.2), i.e.
φM bv = φM bc − ( φM bc − φM bfc) (2γ − 1)
. . . D3.3(2)
FIGURE D3.2 RELATIONSHIP BETWEEN φ M bv AND γ FOR 0 ≤ β ≤ 1.0
D3.3 Calculation of φM b and φM bf as a function of β
The values of φM b and φM bf for use in Equation D3.2(1) shall be calculated from one of the
following:
(a)
φM b and φM bf as continuous functions of β (see Figure D3.3(a)) Calculate the nominal
moment capacity Mb in accordance with Paragraph D2.3.3 and the nominal moment
capacity Mbf shall be calculated in accordance with Paragraph D3.4.3.
(b)
φM b and φM bf as approximate bi-linear functions of β (see Figure D3.3(b)) First,
using the following equation, calculate the degree of shear connection (ψ) of the
composite beam with the whole of the effective portion of the steel beam included,
corresponding to when the section with the flanges only (i.e., web ignored) has
complete shear connection:
ψ = Fccf /Fcc
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. . . D3.3(1)
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AS 2327.1—2003
where
F ccf = compressive force in the concrete slab corresponding to complete shear
connection (β = 1.0) when the web of the steel beam is ignored (i.e.,
γ = 1.0), calculated using Paragraph D3.4.2
F cc = compressive force in the concrete slab corresponding to complete shear
connection (β = 1.0) when the whole of the effective portion of the steel
beam is included (i.e., γ ≤ 0.5), calculated using Paragraph D2.3.2
Second, calculate φMb and φM bf from either of the following pairs of equations
depending on the magnitude of β with respect to ψ:
(i)
For 0 < β ≤ ψ
φM b = [ φMs (ψ − β ) + φM b.ψ β ] / ψ
. . . D3.3(2)
φM bf = [ φMs (ψ − β ) + φM bfc β ] / ψ
. . . D3.3(3)
FIGURE D3.3 DESIGN MOMENT CAPACITY φ M bv AS A FUNCTION OF β WHEN γ > 0.5
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102
For ψ < β < 1.0
φM b = [ φM b.ψ (1 − β ) + φM bc (β − ψ)]/(1 − ψ)
. . . D3.3(4)
φM bf = φM bfc
. . . D3.3(5)
where φMb.ψ is the value of φM b when γ ≤ 0.5 and β = ψ , and M b shall be
calculated using Paragraph D2.3.3.
D3.4 Nominal moment capacities M bfc and M bf for γ = 1.0
D3.4.1 General
When γ = 1.0, the web of the steel beam shall be ignored and the nominal moment capacities
of the composite beam M bfc and M bf determined in accordance with—
(a)
Paragraph D3.4.2 for complete shear connection (ψ ≤ β ≤ 1.0); and
(b)
Paragraph D3.4.3 for partial shear connection (β < ψ).
D3.4.2 Nominal moment capacity Mbfc (ψ ≤ β ≤ 1.0)
The nominal moment capacity M bfc shall be determined in accordance with the following
procedure, referring to Figure D3.4.2 for notation:
(a)
Calculate the following:
(i)
F stf = (A f1 + A f2) f yf
(ii)
d sr
. . . D3.4.2(1)
where
F stf = tensile capacity of the steel beam flanges
d sr = depth at which Fstf acts below the top surface of the slab
(b)
Calculate the following compressive forces:
(i)
F c1 from Equation D2.3.2(2).
(ii)
F c2 from Equation D2.3.2(3).
(iii) F scf from Equation D2.3.2(4).
(c)
Calculate dc , d h , Fccf and finally Mbfc from the following appropriate cases defined by
the bounds on Fstf :
(i)
Case 1 Fstf ≤ Fc1
If Fstf ≤ Fc1, then d h ≤ (Dc − h r); and
dc
= d h = (Dc − h r)Fccf /Fc1
F ccf
= F stf
. . . D3.4.2(2)
M bfc = F ccf (dsr − d c/2)
(ii)
. . . D3.4.2(3)
Case 2 Fc1 < Fstf ≤ (Fc1 + F c2)
If Fc1 < Fstf ≤ (Fc1 + F c2), then (Dc − h r) < d h ≤ Dc; and
dc
= d h = (Dc − h r) + hr(Fstf − Fc1)/Fc2
F ccf
= F stf
. . . D3.4.2(4)
M bfc = F c1[dsr − (D c − h r)/2] + (Fccf − F c1) [d sr − (Dc − h r + dh )/2]
. . . D3.4.2(5)
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(iii) Case 3 (Fc1 + Fc2) < Fstf < (F c1 + Fc2 + 2Fscf )
If (Fc1 + Fc2) < Fstf < (Fc1 + F c2 + 2Fscf ), then D c < dh ≤ (Dc + t f1); and
dc
= Dc
F ccf
= F c1 + Fc2; Fsc = Fstf − F ccf
. . . D3.4.2(6)
dh
= D c + t f1 Fsc/(2Fscf )
. . . D3.4.2(7)
M bfc = F c1[dsr − (D c − h r)/2] + Fc2[d sr − Dc + h r/2]
+ Fsc[dsr − (Dc + d h )/2]
. . . D3.4.2(8)
NOTE: The equations for the unusual case when the compressive stress zone falls within the
bottom flange of the steel beam have not been formulated.
FIGURE D3.4.2 NOTATION FOR M bfc DETERMINATION ( γ = 1.0, β = 1.0)
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D3.4.3 Nominal moment capacity Mbf (0 < β < ψ )
The nominal moment capacity Mbf shall be determined in accordance with the following
procedure, referring to Figure D3.4.3 for notation:
(a)
Calculate Fstf and d sr from Paragraph D3.4.2(a).
(b)
Calculate Fc1, Fc2 and Fscf from Paragraph D3.4.2(b).
(c)
Calculate F ccf from Paragraph D3.4.2(c) for the applicable case corresponding to
complete shear connection.
(d)
Calculate Fcpf from either—
(i)
when the strength of the shear connection is known—
F cpf = n i f ds < F ccf ; or
(ii)
when the degree of shear connection β is specified—
F cpf = β Fcc < Fccf
(e)
If Fcpf ≤ F c1 , then dc ≤ (D c − h r); and
dc
(ii)
= (Dc − h r)Fcpf /Fc1
. . . D3.4.3(4)
If Fcpf > Fc1, then (D c − h r) < d c ≤ D c, and
dc
= (Dc − h r) + h r (F cpf − F c1)/F c2
. . . D3.4.3(5)
Calculate d h from the following:
(i)
If Fsc ≤ 2Fscf , then D c < d h ≤ (D c + t f1); and
dh
(ii)
= D c + t f1 Fsc/(2Fscf )
. . . D3.4.3(6)
If Fsc > 2F scf , then (Dc + D s − t f2) < d h ≤ (Dc + Ds); and
dh
(h)
. . . D3.4.3(3)
Calculate d c from one of the following as appropriate:
(i)
(g)
. . .D3.4.3(2)
Calculate—
F sc = F stf − Fcpf
(f)
. . . D3.4.3(1)
= D c + Ds − t f2 + (Fsc − 2Fscf)/(2f yf b sf2 )
. . . D3.4.3(7)
Calculate M bf from the appropriate case following, defined by the bounds on Fcpf and
F scf , using the relevant values of d c and d h from Steps (f) and (g) respectively:
(i)
Case 1 Fcpf ≤ Fc1 and F sc ≤ 2Fscf
If Fcpf ≤ F c1 and Fsc ≤ 2Fscf , then
M bf = F cpf (dsr − d c/2) + Fsc[dsr − (D c + d h )/2]
. . . D3.4.3(8)
where
d c is obtained from Equation D3.4.3(4); and
d h is obtained from Equation D3.4.3(6).
(ii)
Case 2 Fcpf ≤ Fc1 and F sc > 2Fscf
If Fcpf ≤ F c1 and Fsc > 2Fscf , then
M bf = F cpf (dsr − d c/2) + 2Fscf [dsr − D c − t f1 /2]
+ F b[dsr − (Dc + Ds − t f2 + d h )/2]
. . . D3.4.3(9)
where
d c is obtained from Equation D3.4.3(4);
d h is obtained from Equation D3.4.3(7); and
F b = Fsc − 2Fscf
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(iii) Case 3 Fcpf > F c1 and Fsc ≤ 2Fscf
If Fcpf > Fc1 and Fsc ≤ 2Fscf , then
M bf = F c1[dsr − (Dc − h r)/2] + (F cpf − Fc1)[d sr − (D c − h r + dc )/2]
. . . D3.4.3(10)
+ Fsc [dsr − (Dc +d h )/2]
where
d c is obtained from Equation D3.4.3(5); and
d h is obtained from Equation D3.4.3(6).
(iv)
Case 4 Fcpf > F c1 and Fsc > 2Fscf
If Fcpf > Fc1 and Fsc > 2Fscf , then
M bf = F c1[dsr − (D c − h r)/2] + (Fcpf − Fc1)[dsr − (Dc − h r + dc)/2]+
2Fscf [dsr − (Dc + t f1 /2)] + F b [dsr − (D c + Ds − t f2 + dh )/2] . . . D3.4.3(11)
where
d c is obtained from Equation D3.4.3(5);
d h is obtained from Equation D3.4.3(7); and
F b = Fsc − 2Fscf
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FIGURE D3.4.3 NOTATION FOR M bf DETERMINATION ( γ = 1.0, 0.0 < β <1.0)
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AS 2327.1—2003
APPENDIX E
FLOW CHARTS
(Informative)
E1 OVERALL DESIGN
Figure E1 shows the overall design process in the form of a flow chart. The shaded boxes
indicate the relevant Section of the Standard in which the particular requirements are located.
The horizontal dashed lines indicate the limits of the design procedures of the Standard
(except for Section 4), and dotted flows outside these limits refer to design in accordance
with the other Standards noted.
E2 CALCULATION OF EFFECTIVE CROSS-SECTION
The procedure to be followed when calculating the effective section of a composite beam
cross-section is shown diagrammatically in Figure E2 and is affected by the degree of shear
connection β of the beam cross-section. The procedure would be carried out for each
different potentially critical cross-section.
NOTE: When an initial assessment is made to determine the effective section of a composite beam
cross-section, the degree of shear connection β may not be known, in which case it is conservative
to ignore composite action and to calculate the depth of the compressive stress zone assuming only
the steel beam is present. In critical cases it will be beneficial to redetermine the effective section
once β is known more accurately.
E3 GENERAL PROCEDURE FOR STRENGTH DESIGN
The procedure to be followed for strength design is shown in Figure E3 in the form of a
flowchart. The shaded boxes indicate the Clause or Section of the Standard relevant to the
particular activity in the procedure.
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FIGURE E1 (in part) FLOW CHART OF OVERALL DESIGN PROCESS
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AS 2327.1—2003
FIGURE E1 (in part) FLOW CHART OF OVERALL DESIGN PROCESS
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FIGURE E2 FLOW CHART SHOWING PROCEDURE FOR CALCULATING THE
EFFECTIVE SECTION OF A COMPOSITE BEAM CROSS-SECTION
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AS 2327.1—2003
FIGURE E3 (in part) FLOW CHART SHOWING GENERAL
PROCEDURE FOR STRENGTH DESIGN
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FIGURE E3 (in part) FLOW CHART SHOWING GENERAL
PROCEDURE FOR STRENGTH DESIGN
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AS 2327.1—2003
E4 PROCEDURE FOR DESIGN OF LONGITUDINAL SHEAR REINFORCEMENT
FOR TYPE 1, 2 AND 3 SHEAR SURFACES
The procedure to be followed for the design of longitudinal shear reinforcement for Type 1, 2
and 3 shear surfaces, is shown in Figure E4 in the form of a flowchart. The shaded boxes
indicate the Clause of the Standard relevant to the particular activity in the procedure.
FIGURE E4 FLOW CHART SHOWING PROCEDURE FOR DESIGN OF LONGITUDINAL
SHEAR REINFORCEMENT (TYPES 1, 2 AND 3)
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APPENDIX F
CONSTRUCTION STAGES AND MINIMUM CONSTRUCTION LOADS
(Normative)
F1 CONSTRUCTION STAGES
The construction stages used for the purposes of assessing construction loads and the
initiation and development of composite action shall be as defined in Clause 4.2 and shown
diagrammatically in Figure F1(A) and pictorially in Figure Fl(B). The nominal minimum
construction loads associated with each stage shall be determined in accordance with
Paragraph F2.
FIGURE F1(A) CONSTRUCTION STAGES 1 TO 6
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AS 2327.1—2003
Construction Stage 1
Construction Stage 1 (continued)
Construction Stage 2
Construction Stage 3
Construction Stages 5 and 6
Construction Stages 5 and 6 (continued)
FIGURE F1(B) ILLUSTRATIONS OF CONSTRUCTION STAGES 1 TO 6
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F2 MINIMUM NOMINAL LOADS FOR CONSTRUCTION
F2.1 General
The nominal construction loads specified in the Paragraphs below are the minimum values to
be used in assessing the structural adequacy of the profiled steel sheeting and the steel beam
during Construction Stages 1 to 4, and for the design of the composite beam during
Construction Stages 5 and 6. When formwork other than profiled steel sheeting is used,
construction loads shall be determined in accordance with AS 3610. Loads of variable
position shall be placed to cause the most adverse effect on the member.
F2.2 Construction Stage 1
F2.2.1 Profiled steel sheeting
During Construction Stage 1, the minimum nominal loads assumed to act on the profiled steel
sheeting shall be taken as follows:
(a)
Dead load of steel sheeting.
(b)
Live loads consisting of—
(i)
a uniformly distributed load of 1.0 kN/m 2 ; or
(ii)
a concentrated load of 1.0 kN applied in the edge pan or 2.0 kN elsewhere,
concentrated on an area of 0.1 m × 0.1 m.
F2.2.2 Steel beam
During Construction Stage 1, the minimum nominal loads assumed to act either directly or
indirectly on the steel beam shall be taken as follows:
(a)
Dead loads, consisting of the weight of the steel beam plus any formwork supported by
the beam.
(b)
Live loads consisting of—
(i)
a concentrated load of 10.0 kN applied to the top flange of the steel beam
anywhere within the span; or
(ii)
a uniformly distributed load acting on the formwork supported by the beam,
taken as—
(A)
0.5 kN/m 2 if the tributary area A is less than or equal to 23 m2 ;
(B)
0.3 kN/m 2 if the tributary area A is greater than or equal to 46 m2 ; or
(C)
varying linearly between 0.5 and 0.3 kN/m 2 if the tributary area A is
between 23 and 46 m 2 .
NOTE: The tributary area A is the sum of all areas of formwork supported by the steel
beam. When the formwork comprises profiled steel sheeting, the tributary area should be
calculated assuming one-way action of the sheeting.
F2.3 Construction Stage 2
F2.3.1 Profiled steel sheeting
During Construction Stage 2, the minimum nominal loads assumed to act on the profiled steel
sheeting shall be taken as follows:
(a)
Dead loads, consisting of the weight of—
(i)
the steel sheeting; and
(ii)
the slab reinforcement placed on the sheeting.
NOTE: A typical allowance for slab reinforcement is 0.1 kN/m 2 per 100 mm of overall
depth.
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(b)
AS 2327.1—2003
Live loads consisting of—
(i)
a uniformly distributed load of 5.0 kN/m2 (which includes an allowance for
stacked materials of 4.0 kN/m 2); or
(ii)
a concentrated load of 1.0 kN applied in the edge pan or 2.0 kN elsewhere,
concentrated on an area of 0.1 m × 0.1 m.
F2.3.2 Steel beam
During Construction Stage 2, the minimum nominal loads assumed to act either directly or
indirectly on the steel beam shall be the same as those for Construction Stage 1.
F2.4 Construction Stage 3
F2.4.1 Profiled steel sheeting
During Construction Stage 3, the minimum nominal loads assumed to act on the profiled steel
sheeting shall be taken as follows:
(a)
Dead loads as for Stage 2, plus—
(i)
the weight of fresh concrete (see Note 1); and
(ii)
the additional weight of fresh concrete due to ponding (see Note 2).
NOTES:
(b)
1
The density of normal-weight concrete may vary from 2100 kg/m 3 to 2800 kg/m 3 depending
on geographical location (see AS 3600).
2
The additional weight due to ponding of the concrete on the sheeting may be calculated by
assuming an average increase in slab depth equal to 0.7 times the maximum deflection of
the sheeting. However, if the steel beams supporting the sheeting also deflect appreciably,
then the effect of this movement should also be considered in the calculation.
Live loads consisting of—
(i)
a uniformly distributed load of 1.0 kN/m 2 ; or
(ii)
a load of 2.0 kN/m 2 , distributed over an area of 1.6 m × 1.6 m anywhere within
the span, for localized mounding during concrete placement.
F2.4.2 Steel beam
During Construction Stage 3, the minimum nominal loads assumed to act either directly or
indirectly on the steel beam shall be taken as follows:
(a)
Dead loads as for the steel beam during Stage 2, plus—
(i)
the weight of fresh concrete on the tributary area A; and
(ii)
the additional weight of fresh concrete due to ponding.
NOTE: The combined deflections of the steel beams and the formwork as they affect the
overall magnitude of ponding need to be considered.
(b)
Live loads, consisting of a uniformly distributed load acting on the formwork, taken
as—
(i)
1.0 kN/m 2 if the tributary area A is less than or equal to 23 m2 ;
(ii)
0.6 kN/m 2 if the tributary area A is greater than or equal to 46 m2 ; or
(iii) varying linearly between 1.0 and 0.6 kN/m2 if the tributary area A is between 23
and 46 m 2 .
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F2.5 Construction Stage 4
During Construction Stage 4, potential damage to the shear connection shall be avoided.
NOTE: Damage to the shear connection can be avoided by preventing either the imposition of
significant live loads on the slab, or the removal of any falsework or props supporting the slab or
the steel beam; or alternatively by back-propping the slab, or the steel beam or both (see also
Clause 11.4).
F2.6 Construction Stages 5 and 6
During Construction Stages 5 and 6, the minimum nominal loads assumed to act on the
composite beam shall include all of the following:
(a)
Dead loads consisting of the weight of—
(i)
the steel beam plus any applied finishes;
(ii)
the concrete slab plus any applied finishes; and
(iii) any other items of permanent construction (e.g., suspended ceilings, permanent
partitions, reticulated services).
(b)
(c)
Live loads, consisting of uniformly distributed loads placed over the tributary area of
the concrete slab (see Note 1), of magnitude—
(i)
1.0 kN/m 2 if no levels above are directly supported by the beam (see Note 2); or
(ii)
if the beam provides direct support to levels of construction above, 1.0 kN/m2 on
the topmost level and 0.25 kN/m 2 on each level providing support to the next
level above.
Unless otherwise provided in the project drawings or specification, a live-load
allowance for stacked materials of 4.0 kN/m2 distributed over an area of 2.5 m by
2.5 m, and located anywhere within the span.
NOTES:
1
The tributary area of the concrete slab is determined taking into account the presence of any
props supporting the slab and whether the slab exhibits either one-way or two-way action (see
Clause 5.3.5). Imposed load reduction may be applied in accordance with AS/NZS 1170.1.
2
In multistorey construction, where the floor structures of a number of lower levels are used to
provide support for the construction of each new level, the loads carried by the lowest
supporting floor during this period may well exceed the design loads for the strength
limit-state, and this loading case needs to be checked separately. Methods for determining these
loads, which depend primarily on the number of supporting floors and the rigidity of each floor
at the relevant time, are given in references cited in AS 3610, Supplement 2.
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AS 2327.1—2003
APPENDIX G
DESIGN FOR FIRE RESISTANCE OF CONCRETE SLABS
(Normative)
G1 DEFINITIONS
For the purpose of this Appendix, the definitions given in Clause 10.2 shall apply.
G2 SOLID SLABS
Solid slabs shall be designed to achieve their required fire-resistance level in accordance with
AS 3600.
G3 COMPOSITE SLABS
Composite slabs shall be designed to achieve their required fire-resistance level in terms of
structural adequacy, insulation and integrity.
The period of structural adequacy of a composite slab shall be predicted by a recognized
method of calculation (see Note).
A composite slab shall be deemed to have one of the fire-resistance periods for insulation
given in Table G1, if the overall depth of the slab (Dc) is not less than the appropriate value
given in the Table.
TABLE G1
REQUIREMENTS FOR INSULATION PERIOD OF COMPOSITE SLAB
Minimum slab depth (D c ) mm
Fire-resistance
period (minutes)
Normal weight concrete
Lightweight concrete
60
90
90
90
100
100
120
120
115
180
140
135
240
170
150
A composite slab shall be deemed to have integrity maintained for a particular fire-resistance
period provided the profiled steel sheeting forms a continuous membrane with the lap joints
being cast into and sealed by the concrete.
NOTE: An acceptable method of calculation is given in Reference 7, Appendix I.
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APPENDIX H
INFORMATION FOR DETERMINATION OF ACTION EFFECTS
(Informative)
H1 SUPPORT REACTION POSITIONS
For the purpose of determining the effective span of a composite beam, the support reaction
may be assumed to act in one of the following positions:
(a)
When the steel beam is supported on a wall or plinth, the end reaction shall be assumed
to be at the lesser of Ds/2 or bs/2 in from the front face of the support (Figure H1(a)).
(b)
When the steel beam is attached through a simple steel connection to a relatively rigid
wall or column, the end reaction shall be assumed to be at the face of the supporting
member (Figure H1(b)).
(c)
When the steel beam is attached through a steel connection to a flexible wall or
column, the end reaction shall be assumed to be at the centre of the supporting member
(Figure H1(c)).
(d)
When the steel beam is connected to the web of a supporting steel beam, the end
reaction shall be assumed to be at the centre of the supporting member (Figure H1(d)).
FIGURE H1 (in part) ASSUMED POSITION OF END SUPPORT REACTIONS OF A
COMPOSITE BEAM
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FIGURE H1 (in part) ASSUMED POSITION OF END SUPPORT REACTIONS OF A
COMPOSITE BEAM
H2 TRIBUTARY AREAS
The area of formwork or slab contributing load to a beam may be taken as one of the
following as appropriate:
(a)
A solid slab shall be assumed to exhibit two-way action (Figure H2(a)).
(b)
A composite slab shall be assumed to exhibit one-way action in the direction of the
sheeting ribs (Figure H2(b)).
(c)
The presence of any props supporting a composite slab from below shall be considered
(Figure H2(c)).
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FIGURE H2 TRIBUTARY AREAS FOR STRENGTH LIMIT STATE
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AS 2327.1—2003
APPENDIX I
BIBLIOGRAPHICAL REFERENCES
(Informative)
Attention is drawn to the following documents referred to in various Notes:
1
PATRICK M., DAYAWANSA P.H., WILKIE R. AND WATSON K.B., Partial Shear
Connection Strength Design of Simply-Supported Composite Beams—Draft Revision
of AS 2327, Part 1. Steel Construction, Australian Institute of Steel Construction,
Sydney, March 1994, pp 2-23.
2
PATRICK M. and WILKIE R., Tubeline and DuraGal Structural Steel Hollow-Section
Composite Beams. BHP Research Report No. BHPR/SM/R/013, March 1995.
3
PATRICK M., EADIE I. AND WATSON K.B., Development of a Suitable SemiRigid Composite Connection. 4th Pacific Structural Steel Conference, Singapore,
October 1995.
4
WYATT T.A., Design Guide on the Vibration of Floors. Publication 076, The Steel
Construction Institute (UK), Ascot, Berks, 1989.
5
PATRICK M., DAYAWANSA P.H. and WATSON K.B., A New Reinforcing
Component for Preventing Longitudinal Shear Failure of Composite Edge-Beams. 4th
Pacific Structural Steel Conference, Singapore, October 1995.
6
PATRICK M., et al., Australian Composite Structures Standard AS 2327, Part 1:
Simply-Supported Beams. Steel Construction, Australian Institute of Steel
Construction, Vol. 29, No. 4, December 1995, pp. 2-40.
7
BENNETTS I.D., PROE D.J., PATRICK M. AND POON S.L., Design for Fire
Resistance of Composite Slabs Incorporating BONDEK II. 1994 Australasian
Structural Engineering Conference, Sydney, September 1994, Vol. 2, pp 651-656.
8
Composite Beam Design and Safe Load Tables. Australian Institute of Steel
Construction, Sydney 1989.
9
CHICK DAYAWANSA, D and PATRICK, M, ‘Strength Design of Simply-Supported
Composite Beams with Large Steel Web Penetrations’, Proceedings, Australasian
Structural Engineering Conference (ASEC-98), Auckland, September, 1998, pp159166.
10
MURRAY T.M., ALLAN, D.E. and UNGAR E.E., Floor Vibrations Due to Human
Activity, American Institute of Steel Construction and Canadian Institute of Steel
Construction, 1997.
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NOTES
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