john hooper presentation

7/30/2019 John Hooper Presentation

1/41

PEERTall BuildingSeismic Design

Guidelines

Preliminary DesignRecommendations &

Performance StudiesJohn HooperPrincipal & Director of Earthquake Engineering

Magnusson Klemencic Associates

SEAW November 30, 2010


2/41


3/41

Structural Configuration

Simple arrangement of structuralelements

Clearly defined load paths Complicated configurations andgeometries complicate behavioravoid

to the extent possible


4/41

Changes in Building Stiffness and Mass

System Configuration


5/41

Repositioning of Bracing Elements



6/41

Multiple Towers on a Common Base



7/41

Column Transfers and Offsets



8/41

Gravity Induced Shear Forces



9/41

Limited Connectivity of Floor Diaphragms



10/41

Concentration of Diaphragm Demands



11/41

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


12/41

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


13/41

WIDTH?

Wind


14/41

WIDTH?

Wind


15/41

Significantly Impact Shear and Flexural Demands

Higher Mode Effects


16/41

Higher Mode Effects


17/41

Column Demands Due to Outrigger Over Strength

Outrigger Elements


18/41

Serviceability Base Shears


19/41

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


20/41


All provisionsfollowed exceptheight limits

Design A


21/41


All provisionsfollowed exceptheight limits

Seismic Ss = 2.1, S1 = 0.7 Site class C SDC D

Wind 85 mph, exposure B

Design A


22/41


PBD based on LA TallBuildings Guidelines(2008)

Seismic design todisregard all coderequirements

Design verified bynonlinear analysis

Wind and gravitydesign to follow code

Design B


23/41


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


24/41


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


25/41

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


26/41

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


27/41

Tower and Core Wall Isometric


28/41

Tower Plan


29/41

Design B & C Seismic Hazard Spectra


30/41

Design B & CServiceability Model

3-D Model usingETABS

Elastic RSA

Model IncludedSlab Outriggers


31/41

Design A Design B Design C

Summary of ResultsCode & Serviceability


32/41

Design B Design C


33/41

Coupling Beam

Reinforcement

Design A

Design B

Design C


34/41

Vertical Wall

Reinforcement Design CDesign A

Design B


35/41

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


36/41

Design B Coupling Beam Rotations


37/41

Design C Coupling Beam Rotations


38/41

Design B Story Drifts


39/41

Design C Story Drifts


40/41

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


41/41

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

john hooper presentation

Documents