2015 tongji-ubc symposium jeremy atkinson [email protected] seismic performance of outriggered...
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2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Seismic Performance of Outriggered Tall Buildings
Jeremy Atkinson
MASc CandidateAdvisor: Prof. YangUniversity of British Columbia
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Why are outriggers used?
Typical Reasons:
Architectural expression
Reduce lateral drift
Reduce overturning moment
Reduce foundation demand
Allows more slender core more saleable area
New Reasons:
Better seismic performance
Supplemental energy dissipation / damping
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Research Objectives
Evaluate the performance of conventional and outrigger
buildings
Adapt performance-based design approach for outrigger systems
Verify performance-based design approach
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Prototype Buildings
Survey of Vancouver’s Tallest Buildings
Ductile Shear Wall (R=5.6) and Ductile
Coupled Walls (R=6.8) in central
core
Diagonally reinforced coupling beams
Single slab span to perimeter columns
around core, many with PT slabs
Blade columns
1000 – 1500 m2 (9000 – 12000 ft2) floor
plates
30-60 stories (height 110-200 m)
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Prototype Buildings
Assume a simple but typical Vancouver layout
Coupled walls / Ductile walls
Two C-shaped piers with diagonally-reinforced CBs
Perimeter columns around core
Outrigger in ductile wall direction
Automatically generated, analyzed, and designed using MATLAB +
OpenSees
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Capacity Design
Choose a hierarchy of energy dissipating mechanisms (‘Fuses’)
Provide sufficient reserve strength to other components (‘Brittle Links’)
Ensure desired mechanism forms, even with uncertainty in demands, etc
Ff
Fuse Link
Brittle Links Fuse Link
Brittle LinkF
Δ Δ
F
Brittle Links
Fr
FprobEnsure Fr >
Ff
FrEnsure Fr > Ff
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Traditional Design Approach
1. Elastic analysis for code-
specified hazard level / demands
2. Choose a hierarchy
3. Design Mech. 1 for EQ forces
4. Calculate Mech. 1 Overstrength
5. Design ‘Brittle Links’
6. Design Mech. 2
7. Calculate Mech. 2 Overstrength
8. Design ‘Brittle Links’
9. … Plastic Hinge
Steel Fuse, BRB, etc.
Mech. 1
Mech. 2
The system collapse mechanism is enforced
But how is the performance? Can PBD provide improvements?
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Incremental Dynamic Analysis
0 0.05 0.1 0.150
1
2
3
4
5
6
Maximum Story Drift Ratio
S(T
1) [g
]
IDA Response of Simple Model
SCT
SMT
CMR ~ 12
Prototype:• 40 story• commercial use• ductile wall / coupled wall• outrigger in ductile wall
direction• 1250m2 plate• designed using traditional
approach
2015 TONGJI-UBC SYMPOSIUM
Jeremy [email protected]
Ongoing…• More prototype designs of various configurations
• Comparison of outrigger and conventional buildings
• More advanced analysis
Next Steps…
• Adapt and implement performance-based design procedure
• Comparison of performance-based and traditional designs
