FEASIBILITY STUDY OF HYBRID WOOD STEEL STRUCTURES By:Yalda Khorasani 08/11/2010 Feasibility Study of Hybrid Wood Steel Structures by Yalda Khorasani1 of

FEASIBILITY STUDY OF HYBRID WOOD STEEL

STRUCTURES

By:Yalda Khorasani

08/11/2010

Feasibility Study of Hybrid Wood Steel Structures by

Yalda Khorasani 1 of 35

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

08/11/2010Feasibility Study of Hybrid

Steel Timber Structures2 of 35

Properties of Steel, Wood and Concrete



• 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



Fig. 2. Stress Strain Diagram of Wood-Compression Parallel to Grain



Fig. 3. Stress Strain Diagram of Wood –Compression Perpendicular to Grain



Fig. 3. Stress Strain Diagram of Concrete - Compression



Advantages of Hybrid Wood Steel Structure



• Increase Load Bearing Capacity

• Increased Seismic Performance

• Cost Benefits

• Increased Durability

• Higher Fire Resistance

• Allows Pre-Fabrication

Types of Hybrid Structure



• 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

08/11/2010 Feasibility Study of Hybrid Steel Timber Structures 10 of 20

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




Hybrid Frame:steel as column and timber as beam

Sainsbury’s Dartmouth warehouse in Devon, England

Fig 5. Steel Column-Glulam Roof




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




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



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



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



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




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




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



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



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



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



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



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



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



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.



Table 3. SAPWood material model

SAP WOOD

Wood Shear Wall Hysteretic Models

Linear

Bilinear

SAWS Ten Parameter Model

Evolutionary Parameter Hysteretic (EPHM) Model



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



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



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

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



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



Fig. 18. OSB Shear Wall

Fig. 19. Steel frame modelled with Ansys



Fig. 20. Steel frame with OSB modelled with ANSYS



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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FEASIBILITY STUDY OF HYBRID WOOD STEEL STRUCTURES By:Yalda Khorasani 08/11/2010 Feasibility Study of Hybrid Wood Steel Structures by Yalda Khorasani1 of