Presentation  IV:

Structural Systems for Multistorey Buildings

Yogendra Singh, Ph.D.Professor, Department of Earthquake EngineeringIndian Institute of Technology Roorkeewww.iitr.ac.in

Indo-Norwegian Training ProgrammeIndo-Norwegian Training Programme

Seismic Design of Multi-Storey Buildings:

IS 1893 vs. Eurocode 8

Seismic Design of Multi-Storey Buildings:

IS 1893 vs. Eurocode 8

New Delhi,

26–28 May 2014

New Delhi,

26–28 May 2014

6/4/2014

LOADS AND RESISTING SYSTEMS IN BUILDINGS

VERTICAL LOAD

DEAD LOAD LIVE LOAD SNOW LOAD

SLAB BEAMS

HORIZONTAL FRAMING

HORIZONTAL LOAD

WIND LOAD EARTHQUAKE LOAD

FRAME SHEAR WALL MASONRY INFILLS

VERTICAL FRAMING

LOADS ON BUILDINGS

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COMPONENTS PROVIDING LATERAL RESISTANCE

• Frames • Trusses• Shear Walls• Brick Walls• Stairs• Partitions

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LATERAL LOAD RESISTANCE OF TRADITIONAL BUILDINGS

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LATERAL LOAD RESISTANCE OF MODERN BUILDINGS

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LATERAL LOAD RESISTING STRUCTURAL SYSTEMS

• FRAMES • FRAME-TRUSS• SHEAR WALLS, FRAME-SHEAR WALL &

COUPLED SHEAR WALLS• FRAME-TRUSS-OUTRIGGER SYSTEM• FRAMED TUBE• TUBE-IN-TUBE• END CHANNEL FRAMED TUBE• TRUSSED TUBE• MULTI-CELL TUBE

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STRUCTURAL SYSTEMS IN STEEL

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STRUCTURAL SYSTEMS IN REINFORCED CONCRETE

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FRAME STRUCTURES

• Derive lateral stiffness from rigid joints between beams and columns.

• Provide flexible usage and architectural design.

• Can be used for buildings up to 20 storey height in concrete and 30 storey height in steel can be achieved.

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FRAME ACTION

P P

h

Ph/2 <Ph/2

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BRACED FRAME ACTION

P

h

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RC FRAME STRUCTURES –RESPONSE DURING PAST EARTHQUAKES

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RC FRAME STRUCTURES –RESPONSE DURING PAST EARTHQUAKES

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RC FRAME STRUCTURESSTRUT ACTION OF INFILL PANELS

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RC FRAME STRUCTURESSTRUT ACTION OF INFILL PANELS

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FRAME STRUCTURES IRREGULAR INFILLS

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STEEL FRAME STRUCTURES FAILURE MODES

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STEEL FRAME STRUCTURES FAILURE MODES

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STEEL FRAME STRUCTURES FAILURE MODES

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STEEL FRAME STRUCTURES FAILURE MODES

Backup Bar

Beam Flange

Column FlangeStiffener

Weld Access Hole

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STEEL FRAME STRUCTURES FAILURE MODES

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STEEL FRAME STRUCTURES

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CONCENTRICALLY VS. ECCECTRICALLY BRACED FRAMES

BRACE BRACE

LINK

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FAILURE OF CONCENTRICALLY BRACED FRAMES

BUCKLING OF COMPRESSIVE BRACE

LOAD

AXIAL HINGE IN TENSILE BRACE

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FAILURE OF ECCENTRICALLY BRACED FRAMES

SHEAR YIELDING IN LINK

LOAD

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CONFIGURATIONS OF ECCENTRICALLY BRACED FRAMES

LINKLINK

LINK LINK LINK LINK

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FAILURES OF LINKS IN ECCENTRICALLY BRACED FRAMES

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SHEAR WALL STRUCTURES

• A vertical cantilever, resisting the lateral load primarily in bending.

• Very stiff system and building heights up to 50 storey can be achieved.

• Acts as rigid partition hindering the flexibility of usage. More suitable to residential buildings

• Suitable for service core in office buildings.

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SHEAR WALL STRUCTURES

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SHEAR WALL STRUCTURES

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FRAME-SHEAR WALL SYSTEM

• Frame deforms in shear mode while shear-wall deforms in flexure mode.

• Interaction : In the lower portion the two components press each other, while in the upper portion they pull each other.

• Sharing of the lateral force between the two components is complex.

• Modelling as frames with wide columns.

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FRAME-SHEAR WALL SYSTEM

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FRAME SHEAR WALL ACTION

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SHEAR WALL SYSTEMS - RESPONSE DURING PAST EARTHQUAKES

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COUPLED SHEAR WALLS• Shear wall having opening for windows or

passage.

• Efficiency depends highly on the stiffness of coupling beams. Coupling beams are subjected to very high shear forces and should be appropriately designed.

• Analytical modelling as

Continuum Approach.

Discrete Approach : Frame with wide columns and rigid joints.

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COUPLED SHEAR WALLS

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FRAME WITH CORE AND OUTRIGGER

• Increases efficiency by inducing axial forces in the columns and reducing bending moments in columns and beams.

• In steel, core and out riggers are made of trusses.

• In concrete, shear wall core and store deep girders.

• Modelling as space frames.

• Vertical load behaviour is also modified due to outrigger. 6/4/2014

CORE AND OUTRIGGER SYSTEM

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FRAMED-TUBE SYSTEM

• Closely spaced columns and deep spandrel beam along the periphery

• High lateral rigidity due to hollow tube like section

• Vertical shear transfer takes place at the corner column

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FRAMED-TUBE SYSTEM

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FRAMED-TUBE SYSTEM

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TUBE-IN-TUBE SYSTEM• Outer framed tube

• Inner tube consists of shear wall enclosing service core

• Outer and inner tubes are interconnected through floors

• Interaction between outer and inner tube is similar to that between frame and shear wall

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TRUSSED-TUBE SYSTEM

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SHEAR-LAG IN FRAMED-TUBE SYSTEM

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MULTI-CELL TUBE SYSTEM

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FLAT SLAB SYSTEMS

Drop Panel

Column Head

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FLAT SLAB SYSTEMS

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FLAT SLAB SYSTEMS

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FLAT SLAB SYSTEMS

0

1

2

3

4

5

0 0.2 0.4 0.6 0.8 1

Max

imu

m I

nte

r St

orey

Dri

ft (

%)

Gravity Shear Ratio

Hueste and Wright

ASCE/SEI 41 [NC]

ASCE/SEI 41 [C]

ACI 318-05