FEASIBILITY STUDY OF
HYBRID WOOD STEEL
STRUCTURES
By:Yalda Khorasani
08/11/2010
Feasibility Study of Hybrid Wood
Steel Structures by Yalda
Khorasani
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Outline
Properties of Steel, Wood and Concrete
Types of Hybridization
Case Studies of Hybrid Structures
Software Packages Investigation
Hybrid Steel Frame And Wood Shear Wall
Model
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Properties of Steel, Wood and Concrete
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Steel :
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Wood:
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Good Tension Capacity
Ductile
Linear Stress Strain Relation
Isotropic
Good Compression Capacity
Low tensile Capacity
Stiff
Non-Linear Stress Strain Relation
Orthotropic
High Strength/Density Ratio
Hygroscopic Material
Concrete
Good Compression Capacity

Non Linear Stress Strain

Brittle Fracture
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Timber Structures
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Fig 1. Stress Strain Diagram of Steel-Tension
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Fig. 2. Stress Strain Diagram of Wood-Compression
Parallel to Grain
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Fig. 3. Stress Strain Diagram of Wood –Compression
Perpendicular to Grain
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Fig. 3. Stress Strain Diagram of Concrete Compression
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Advantages of Hybrid Wood Steel Structure
•
Increase Load Bearing Capacity
•
Increased Seismic Performance
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Cost Benefits
•
Increased Durability
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Higher Fire Resistance
•
Allows Pre-Fabrication
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Types of Hybrid Structure
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Component Level Hybridization

Hybrid Bridge Decks and Slabs
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Hybrid Beams/Columns/Braces

Hybrid Joints
•
Structural Level Hybridization

Hybrid Roof Trusses

Vertical Mixed System

Hybrid Steel Moment Frame and Wood Floor
Diaphragm

Hybrid Frames
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Structural Level Hybridization
Roof trusses: combining steel
members in tension with wood
members in compression

Example: in Southridge School in
Surry
Fig. 4 Southridge School Roof Structure
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Structural Level Hybridization
Hybrid Frame:steel as column and
timber as beam

Sainsbury’s Dartmouth warehouse in
Devon, England
Fig 5. Steel Column-Glulam Roof
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Structural Level Hybridization
Building structure
consisting of steel
moment resisting frame
and composite timber
long span floor joist and
plywood flooring
Advantages:

Cost benefits

Better Seismic
Performance

Construction Benefits
Fig 6. Steel Moment Frame and Wood Diaphragm floor
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Structural Level Hybridization
Vertical Mixed System:
structural system comprised of
concrete/steel first floor and
wood upper storeys
Advantages:

Satisfy the Code
requirement for fire
resistance

Increased load bearing
capacity
Fig 7. Concrete first floor, timber structure upper 8 storey
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Component Level Hybridization
Flitch Beam: A steel plate
sandwiched between two wood
joists and bolted together
•
Advantages: Supports heavier loads
over a longer span
Fig 8. Typical flitch beam
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Component Level Hybridization-Hybrid Beams
Wood member reinforced with steel
plates :wood member reinforced by steel
plates on top and bottom or reinforced
with steel plate in between.
•
Advantages :
•
increased in fire resistance
•
improved buckling capacity
•
increased in bending strength
Fig. 9 Hybrid wood steel member
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Component Level Hybridization-Hybrid Beams
Wooden members with built-in
steel materials: H-shape steel
member, square steel bar or
steel plates
Wooden Member
Square Steel
Bar
•
H-Shape
Steel
Member
Glulam
Advantages :
•
increased in fire resistance
•
improved buckling capacity
•
increased in bending
strength
Fig. 10 Hybrid wood steel member
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Component Level Hybridization
Hybrid Bridge Deck: similar to composite
construction where two different
materials are bound together so that they
act together as a single unit from a
structural point of view.



longitudinally laminated prestressed
wood decking
steel girders
shear bulkheads: shear studs in
concrete filled holes
Fig. 11 Hybrid bridge deck
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Component Level Hybridization
Hybrid DuctileTimber Joint: Similar
to post-tensioned precast concrete
building systems.
Can be used for beam-column, wall
foundation or column-foundation
Fig 12. Hybrid Joint
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Hybrid Steel Concrete Structure
Type=Component level
Composite reinforced
concrete and steel moment
frame structures
Advantages=
 Cost saving
 Longer span
 Minimize field labour
Joint Detail=
 Through beam
 Through column
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Fig. 13. Joint Detail
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Hybrid Steel-Timber Structure
Type = Component Level
Six storey building uses
post-tensioned steel tendons
in timber frames and
structural walls.
Advantages=
 Increased seismic
performance
 Rapid erection
 Economical connections
between the large timber
elements
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Fig. 14. Post tensioned members
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Hybrid Concrete- Steel-Timber
Structure
Type = Component + Structural
Level
Reinforced concrete structure
first storey and the second to
fifth stories have a timber-based
hybrid structure with built-in
steel materials
Advantages=
 Satisfy Code requirement
for fire safety
 Increased buckling capacity
Fig. 15. Hybrid members
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ANSYS
Types of analysis: Static, modal, harmonic,
transient dynamic, spectrum, buckling,
explicit dynamic analysis
Capable of modelling:
Linear and non-linear material
Isotropic and Orthotropic material
Composit and layered material
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ANSYS
Linear Material
Elastic Isotripic
Non-Linear Material
Elastic
Inelastic
Specialized Material
ViscoElastic
Gasket
Elastic Anisotropic
Hyperelastic
Rate Independant
Curve Fitting
Joint Elastic
Elastic Orthotropic
Multilinear Elastic
Rate Dependant
Prony
Creep
Non Metal Plasticity
Maxwell
Composites
Cast iron
Table 1. Ansys material library
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SeismoStruct
Types of analysis: Dynamic and static
time-history, conventional and adaptive
pushover, incremental dynamic analysis,
eigenvalue, and non-variable static loading
Capable of modelling: Concrete and steel
but not wood
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SeismoStruct
Steel
Bilinear steel model
Reinforced Concrete
Trilinear concrete model
Nonlinear constant confinement
concrete model
Menegotto-Pinto steel model
Composites
Nonlinear FRP-confined
concrete model
Superelastic shape-memory
alloys model
Nonlinear constant confinement
concrete model with tension softening
Monti-Nuti steel model
Trilinear FRP model
Nonlinear variable confinement
concrete model
Nonlinear constant confinement model
for high-strength concrete
Bilinear steel model
Elastic material model
Table 2. SeismoStruct material model
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SAPWood
Types of analysis: Traditional nonlinear
time domain earthquake excitation,
Incremental Dynamic Analysis (IDA)
Capable of modelling: Wood structure,
shear wall and dry wall, but not steel
structure.
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SAP WOOD
Wood Shear Wall Hysteretic Models
Linear
Bilinear
SAWS Ten Parameter Model
Evolutionary Parameter Hysteretic (EPHM) Model
Table 3. SAPWood material model
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OpenSees Navigator
Types of analysis: Static, transient and
eigenvalue
Capable of modelling:
 Linear and non linear material (wood, steel
concrete)
 Cannot model layered and composite materials
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OpenSees Navigator
Uni axial Material
nD Material
BoucWen
ElasticCrossAnisotropic3D
Concrete01
ElasticIsotropic
Concrete02
FluidSolidPorous
Concrete03
J2Plasticity
Elastic
MultiaxialCyclicPlasticity
ElasticNoTension
PlaneStress
ElasticPP
PlateFiber
ElasticPPGap
PressureDependMultiYield
Fatigue
PressureDependMultiYield02
Hardening
PressureDependentElastic3D
Hysteretic
PressureIndependMultiYield
MinMax
Template3DElastoPlastic
Parallel
Series
Steel01
Steel02
Viscous
Table.4. OpenSees Navigator material model
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Shear Wall/Diaphragm
Diaphragms and shear
walls, constructed with
wood structural panels
such as oriented strand
board (OSB) and
plywood, provide the
primary lateral load
resisting system in many
types of construction.
Fig. 16. OSB Shear Wall
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ANSYS Modelling
W 460 x 106
W 460 x 106
4m
W 310 x 97
W 310 x 97
15 kN
Steel frame-OSB shear
wall
35 kN
6m
W 310 x 97
W 310 x 97
Type analysis: Static
10 m
Purpose of analysis: See
the effect of wood shear
wall on deformation of the
steel frame
Fig.17 Steel frame wood shear wall model
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ANSYS Modelling
Fig. 18. OSB Shear Wall
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Analysis #1= Steel frame w/o
shear wall
Analysis #2 = Steel frame + shear
wall
Modelling OSB as linear,
orthotropic with average
properties of the 3 layers
Analysis #3 = Steel frame + shear
wall
Modelling OSB as layered
element with three linear
orthotropic layers
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Fig. 19. Steel frame modelled with Ansys
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Fig. 20. Steel frame with OSB modelled with
ANSYS
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SUMMARY OF THE RESULT
ANALYSYS #
DEFLECTION(mm)
1
11.05
2
2.07
3
3.1
Table 5. Summary of the result
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