design of a 35 story building in los angeles using the ladbs performance based design methodology la...
TRANSCRIPT
6/19/13
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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
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Creative Thinkers, Cleverly Disguised as Engineers.
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. of
suspended 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
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Creative Thinkers, Cleverly Disguised as Engineers.
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
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Creative Thinkers, Cleverly Disguised as Engineers.
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
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Creative Thinkers, Cleverly Disguised as Engineers.
Main Results • Shear forces Elevator Core
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Creative Thinkers, Cleverly Disguised as Engineers.
Main Results • Maximum Drift
Drift Corner Node H1 (EW)
-‐20246810121416182022242628303234
-‐0.04 -‐0.02 0.00 0.02 0.04Drift
Level
EQ1
EQ2
EQ3
EQ4
EQ5
EQ6
EQ7
MEAN
MEAN+STDEV
MEAN-‐STDEV
Drift Corner Node H2 (EW)
-‐20246810121416182022242628303234
-‐0.03 -‐0.02 -‐0.01 0.00 0.01 0.02 0.03Drift
Level
EQ1
EQ2
EQ3
EQ4
EQ5
EQ6
EQ7
MEAN
MEAN+STDEV
MEAN-‐STDEV
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Creative Thinkers, Cleverly Disguised as Engineers.
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
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Creative Thinkers, Cleverly Disguised as Engineers.
Advantages • PBD allow us to Optimize the
performance of elements of the Lateral Force Resisting System
• NLDA better captures changing inelastic damage state of the structure
• Directly addresses the level of redundancy & safety of the structure
• Increased Useable space due to elimination of frame beams and columns of Dual System
• More flexibility for parking circulation
• More flexibility for distribution of Mech/Elec systems
• Reduction of Materials from Conventional 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
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Creative Thinkers, Cleverly Disguised as Engineers.
Summary • Performance Based Design
(PBD) better captures the complex sway effects of tall buildings
• PBD directly addresses the level of redundancy & safety of the building structure
• PBD is a good alternative for owners to increase useable space and reduce construction materials.
• PBD takes advantage of Leading Edge Design tools and methods, and latest knowledge in tall building design.
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Creative Thinkers, Cleverly Disguised as Engineers.
Thank you!