feasibility study of hybrid wood steel structures by:yalda khorasani 08/11/2010 feasibility study of...
TRANSCRIPT
FEASIBILITY STUDY OF HYBRID WOOD STEEL
STRUCTURES
By:Yalda Khorasani
08/11/2010
Feasibility Study of Hybrid Wood Steel Structures by
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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 : Good Tension Capacity Ductile Linear Stress Strain Relation Isotropic
• Wood: 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
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
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• Increase Load Bearing Capacity
• Increased Seismic Performance
• Cost Benefits
• Increased Durability
• Higher Fire Resistance
• Allows Pre-Fabrication
Types of Hybrid Structure
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• Component Level Hybridization Hybrid Bridge Decks and Slabs 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
• Advantages :• increased in fire
resistance• improved buckling
capacity• increased in bending
strength
Fig. 10 Hybrid wood steel member
Square Steel
Bar
Wooden Member
H-Shape
Steel
MemberGlulam
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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
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 Fig. 13. Joint Detail
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Hybrid Steel-Timber StructureType = 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 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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ANSYSTypes of analysis: Static, modal, harmonic, transient dynamic, spectrum, buckling, explicit dynamic analysisCapable of modelling:
Linear and non-linear material Isotropic and Orthotropic materialComposit and layered material
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Table 1. Ansys material library
ANSYS
Linear Material Non-Linear Material Specialized Material
Elastic Isotripic Elastic Inelastic 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
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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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Table 2. SeismoStruct material model
SeismoStruct
Steel Reinforced Concrete Composites
Bilinear steel model Trilinear concrete model Nonlinear FRP-confined concrete model
Menegotto-Pinto steel model
Nonlinear constant confinement concrete model Superelastic shape-memory
alloys model
Monti-Nuti steel model
Nonlinear constant confinement concrete model with tension softening
Trilinear FRP model
Bilinear steel model
Nonlinear variable confinement concrete model
Elastic material model
Nonlinear constant confinement model for high-strength concrete
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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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Table 3. SAPWood material model
SAP WOOD
Wood Shear Wall Hysteretic Models
Linear
Bilinear
SAWS Ten Parameter Model
Evolutionary Parameter Hysteretic (EPHM) 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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Table.4. OpenSees Navigator material model
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
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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.
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Fig. 16. OSB Shear Wall
ANSYS Modelling
Steel frame-OSB shear wall
Type analysis: Static
Purpose of analysis: See the effect of wood shear wall on deformation of the steel frame
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10 m
4m6m
35 kN
15 kN
W 460 x 106
W 460 x 106W 3
10 x
97
W 3
10 x
97
W 3
10 x
97
W 3
10 x
97
Fig.17 Steel frame wood shear wall model
ANSYS Modelling
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. 18. OSB Shear Wall
Fig. 19. Steel frame modelled with Ansys
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Fig. 20. Steel frame with OSB modelled with ANSYS
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Table 5. Summary of the result
SUMMARY OF THE RESULT
ANALYSYS # DEFLECTION(mm)
1 11.05
2 2.07
3 3.1
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