Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Creative Thinkers, Cleverly Disguised as Engineers.

Design of a 35 Story Building In

Los Angeles Using the LADBS

Performance Based Design

Methodology

LA Tall Building Structural Design Council

Conference

May 3, 2013

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Creative Thinkers, Cleverly Disguised as Engineers.

Contents

•  Project Summary

•  Summary of Design

Development Options

•  Computer Modelling Aspects

•  Main Results

•   Advantages

•  Material Savings

• 

Summary

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Project Summary

•  888 Olive Street Los Angeles (9th & Olive)

•  35 Story Tower – 358 ft.

above grade

•  4 story podium over 2 level

basement

•  700,000 sq. ft. ofsuspended structure.

•  Reinforced Concrete

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Creative Thinkers, Cleverly Disguised as Engineers.

Stage 1

Conventional Design• Dual System• Concrete Shearwalls

• Special Moment Resisting Frames• Linear Dynamic Analysis

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Stage 2

Performance Based• First Trial• Concrete Shearwalls only

• Capacity Design – Cross Sectional Analysis

• Too many walls

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Creative Thinkers, Cleverly Disguised as Engineers.

Stage 3

Performance Based• Optimized Structural Performance• Non-Linear Analysis PERFORM 3D

• Iterations during Peer Review• Modified coupling beams combined

with shearwalls for best combination

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Modelling Aspects•  Fibers – Walls

•  Shear springs – Headers•  Beams – column/slab outriggers

•  Shell (in-plane) – Slabs (podium)

•  Upper and Lower bound stiffness

T1 = 5.8s

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Creative Thinkers, Cleverly Disguised as Engineers.

Modelling Aspects•  Input Earthquake Ground Motions

 –  MCE level

 –  7 Pairs (spectral matching)

 –  PEER GM Database

 –  NEHRP Class C

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Main Results•  Shear forces Elevator Core

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Creative Thinkers, Cleverly Disguised as Engineers.

Main Results•  Maximum Drift

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7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Main Results•  Coupling Beams dissipate

most energy

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Creative Thinkers, Cleverly Disguised as Engineers.

Main Results•  Core walls governed by

maximum shear stress

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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 Advantages•  PBD allow us to Optimize the

performance of elements of theLateral Force Resisting System

•  NLDA better captures changinginelastic damage state of thestructure

•  Directly addresses the level ofredundancy & safety of thestructure

•  Increased Useable space due toelimination of frame beams andcolumns of Dual System

•  More flexibility for parkingcirculation

•  More flexibility for distribution ofMech/Elec systems

• 

Reduction of Materials fromConventional Dual System

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Creative Thinkers, Cleverly Disguised as Engineers.

Material Savings•  Reduction in Materials

from Stage 1 to Stage 3

 –  Concrete 6,000 Cu. Yds

 –  Rebar 3.2 M lbs

 –  Formwork 27,000 s.f.

•  15% reduction in total

structural materials

Stage 1 – Dual System

Stage 3 - PBD

7/17/2019 Design of a 35 Story Building in Los Angeles Using the LADBS Performance Based Design Methodology

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Summary

•  Performance Based Design(PBD) better captures thecomplex sway effects of tallbuildings

•  PBD directly addresses the levelof redundancy & safety of thebuilding structure

•  PBD is a good alternative forowners to increase useablespace and reduce constructionmaterials.

•  PBD takes advantage of

Leading Edge Design tools andmethods, and latest knowledgein tall building design.

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Creative Thinkers, Cleverly Disguised as Engineers.

Thank you!