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PEERTall BuildingSeismic Design
Guidelines
Preliminary DesignRecommendations &
Performance StudiesJohn HooperPrincipal & Director of Earthquake Engineering
Magnusson Klemencic Associates
SEAW November 30, 2010
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Structural Configuration
Simple arrangement of structuralelements
Clearly defined load paths Complicated configurations andgeometries complicate behavioravoid
to the extent possible
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Changes in Building Stiffness and Mass
System Configuration
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Repositioning of Bracing Elements
System Configuration
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Multiple Towers on a Common Base
System Configuration
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Column Transfers and Offsets
System Configuration
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Gravity Induced Shear Forces
System Configuration
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Limited Connectivity of Floor Diaphragms
System Configuration
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Concentration of Diaphragm Demands
System Configuration
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Structural Performance Hierarchy
Identify zone or elements of nonlinearresponse
Establish hierarchy of the nonlinearelements
Incorporate capacity design concepts asappropriate for remaining elements
Confirm hierarchy through nonlinearresponse history analysis
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Structural Performance Hierarchy
Desirable Modes of nonlinear responseinlcude:
Flexural yielding of beams, slabs and shearwalls
Yielding of diagonal reinforcement incoupling beams
Tension yielding in steel braces and steelplate shear walls
Post-buckling compression in steel bracesthat dont support gravity
Tension/compression yielding in BRBs
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WIDTH?
Wind
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WIDTH?
Wind
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Significantly Impact Shear and Flexural Demands
Higher Mode Effects
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Higher Mode Effects
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Column Demands Due to Outrigger Over Strength
Outrigger Elements
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Serviceability Base Shears
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The Performance Study
Three Building Systems
42-story concretecore wall
42-story concretedual system
40-story steel bucklingrestrained braced frame
Building 1
(MKA)
Building 2
(REI)
Building 3
(SGH)
Designs
A
BC
Designs
A
BC
Designs
A
BC
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The Performance Study
All provisionsfollowed exceptheight limits
Design A
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The Performance Study
All provisionsfollowed exceptheight limits
Seismic Ss = 2.1, S1 = 0.7 Site class C SDC D
Wind 85 mph, exposure B
Design A
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The Performance Study
PBD based on LA TallBuildings Guidelines(2008)
Seismic design todisregard all coderequirements
Design verified bynonlinear analysis
Wind and gravitydesign to follow code
Design B
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The Performance Study
2 Design Levels Serviceability MCE
Serviceability check 25-yr return period response spectrum analysis essentially elastic transient drift 0.005
MCE per ASCE 7-05 seven ground motion pairs ductile actions
mean demands expected materials, = 1
brittle actions 1.5 x mean demands specified materials, = 1
transient drift 0.03 Minimum base shear
waived strength controlled by 25-yr EQ and
Wind
Design B
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The Performance Study
Substitute TBIGuidelines for LA TallBuilding Guidelines(2008)
Seismic design todisregard all coderequirements
Design verified bynonlinear analysis
Wind and gravitydesign to follow code
Design C
Seismic Design
Guidelines for TallBuildings
Developed by the Pacific
Earthquake Engineering
Research Center (PEER) as
part of the Tall BuildingInitiative
PEER2010
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The Performance Study 2 Design Levels
Serviceability MCE
Serviceability check 43-yr return period response spectrum analysis
(or nonlinear analysis) essentially elastic: D/C 1.5 C based on nominal strength & code
transient drift
0.005 MCE
per ASCE 7-05 seven ground motion pairs ductile actions
mean demands expected materials, = 1
brittle actions 1.5 x mean demands expected materials, per code
transient story drifts mean 0.03 max 0.045
residual story drifts mean 0.01 max 0.015
Minimum base shear waived strength controlled by 43-yr EQ and Wind
Design C
Seismic Design
Guidelines for TallBuildings
Developed by the Pacific
Earthquake Engineering
Research Center (PEER) as
part of the Tall Buildings
Initiative
PEER2010
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Building 1 ExampleInformation
Located in Los Angeles 42-Story Residential Building 410 ft Tall 108 ft X 107 ft Plan Dimensions Core Wall System Approximate Period: 5 Sec
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Tower and Core Wall Isometric
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Tower Plan
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Design B & C Seismic Hazard Spectra
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Design B & CServiceability Model
3-D Model usingETABS
Elastic RSA
Model IncludedSlab Outriggers
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Design A Design B Design C
Summary of ResultsCode & Serviceability
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Design B Design C
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Coupling Beam
Reinforcement
Design A
Design B
Design C
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Vertical Wall
Reinforcement Design CDesign A
Design B
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Design B & CMCE Model
3-D model using CSI Perform-3D Modeled as inelastic:
Coupling beams Core wall flexural behavior Slabbeams
Modeled as elastic: Core wall shear behavior Diaphragm slabs Columns Basement walls
Model extended to mat
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Design B Coupling Beam Rotations
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Design C Coupling Beam Rotations
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Design B Story Drifts
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Design C Story Drifts
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Building 1 Observations
Core wall shear is the governingdesign parameter & governs wallthickness
Serviceability Design governed overWind Design for Design B & C
Walls thicker for Design C vs. DesignB vs. Design A
Serviceability Demands of Design C> Design B > Design A
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Building 1 Observations
Coupling Beam Reinforcement forDesign C < Design B ~ Design A
Vertical Wall Reinforcement forDesign C > Design B > Design A
Design C Results in Greater StrongPierWeak Coupling BeamPerformance than Design A & B