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7/28/2019 14WCEE Keynote Presentation
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J ack MoehlePacific Earthquake Engineering Research CenterUniversity of California, Berkeley
with contributions fromYousef Bozorgnia, Tony Yang, PEER/BerkeleyRon Klemencic, MKA Seattle
J oe Maffei, Rutherford & ChekenePaul Somerville, SCEC/URS
J ohn Wallace, PEER/UCLA
Performance-BasedSeismic Design of
Tall Buildings in the
United States
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Base
Shear
Deformation
DamageThreshold
CollapseOnset
OPEN
OPEN
OPEN
Performance-based seismic design
Performance LevelsServiceability Safety
Shaking LevelInfrequent Very rare
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OPEN
OPEN
OPEN
Performance-based seismic design
Performance LevelsServiceability SafetyToday
Downtime, days0 1 7 30 180
Casualty rate0.0 0.0001 0.001 0.01 0.25
Tomorrow$, % replacement0 25% 50% 100%
Base
Shear
DamageThreshold
CollapseOnset
Deformation
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Tall buildings
(proposed, approved, or under construction, at last count)Over 75m: San Francisco 38; Los Angeles 61; Seattle
Steve Boland, 2006
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The new generation oftall buildings
Whats different about them? High-performance materials andsystems
Framing systems not satisfying code
prescriptions undefined systems
defined systems beyond permitted heightlimits
MKA
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MKA
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MKA
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MKA
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MKA
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104.11 Alternative materials, design and methods of construction
and equipment. The provisions of this code are not intended to prevent
the installation of any material or to prohibit any design or method of
construction not specifically prescribed by this code, provided that any
such alternative has been approved. An alternative material, design or
method of construction shall be approved where the building official
finds that the proposed design is satisfactory and complies with the intentof the provisions of this code, and that the material, method or work
offered is, for the purpose intended, at least the equivalent of that
prescribed by this code in quality, strength, effectiveness, fire resistance,
durability and safety.
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Building review and approval Peer review
Three-member panel with relevant expertise
Submittal requirements
Seismic design criteria Computer models
Design and verification results
Project specs and construction drawings
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Seismic Design Criteria Earlier approach
Satisfy all coderequirements, withlimited exceptions
Code enhancements
explicit capacity design
performance verificationusing nonlinearanalysis
detailing enhancements
More recent approach
Establish performanceobjectives
explicit capacitydesign as appropriate
performanceverification bynonlinear dynamic
analysis detail as required to
ensure performance
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Seismic performance objectives
after Vision 2000, SEAOC
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None/Slight Moderate Extensive Complete Collapse
Level A 20 15 4 1 0
Level B 19 9 7 4 1
Level C 12 6 9 9 4
Expected No. of Bldgs in each Structural Damage StateHypothetical
Performance
Performance objectives questionGiven 40 tall buildings in a city.Very rare earthquake.
What do you think of this performance scenario?
Holmes et al, 2008
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URS
Seismic
hazardanalysis
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Probabilistic
seismic hazardanalysis
0 2 4 6 8 10Period, sec
Pseudo
Acceleration,g
2.5
2.0
1.5
1.0
0.5
0.00 2 4 6 8 10Period, sec
Pseudo
Acceleration,g
2.5
2.0
1.5
1.0
0.5
0.0
2% in 50 yr UHS2% in 50 yr UHS2% in 50 yr UHS
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Selection and scaling of ground
motions
TARGET
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T1
0 2 4 6 8 10
Period, sec
PseudoAc
celeration,g
2.5
2.0
1.5
1.0
0.5
0.0
2% in 50 yr UHS
2% in 50 yr M6.5 Scenario
Scenario spectrum
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Nonlinear analytical models
FloorNumber
Lateral
system
Gravity-only
system-0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15
-4000
-3000
-2000
-1000
0
1000
2000
3000
Analytical
Experimental
Link beam
Momen
t
Rotation
Bounding Analysis0.25-1.0Gc0.1-0.5Gc
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Model sensitivity: Wall shear
0
10
20
30
40
FloorLevel
-20000-1000001000020000
Wall Shear
Case 1
Case 2
Case 3Case 4
No Factors
ATC 72 (Wallace), 2008
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20000100000
Strong hinge
Intermediate
Intermediate
Weak hinge
Model sensitivity: Wall moment
0
10
20
30
60
50
40
FloorLevel
Moment
intended
yield hinge
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Modeling assumptions
0
10
20
30
40
FloorLevel
-30000 -20000 -10000 0 10000 20000 30000
North South Force (K)
Fiber Hinge
Fiber all
FloorLevel
0
10
20
30
40
FloorLevel
-30000 -20000 -10000 0 10000 20000 30000
North South Force (K)
Fiber Hinge
Fiber all
FloorLevel
0
10
20
30
40
-20000000 0 20000000
Moment about East West axis(K-in)
Fiber Hinge
Fiber all
0
10
20
30
40
-20000000 0 20000000
Moment about East West axis(K-in)
Fiber Hinge
Fiber all
ATC 72 (Wallace), 2008
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Damping
ATC 72 (Deierlein), 2008, after data from Goel and Chopra, 1997
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Calculated dynamic response
Yan
g,
2007
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DBE
CMS, T2
CMS, T1
CMS, T3
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 1 2 3 4 5 6 7 8
Period, sec
SpectralAc
celeration,g
T3
T2
T1
DBE
CMS, T2
CMS, T1
CMS, T3
DBE
CMS, T2
CMS, T1
CMS, T3
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 1 2 3 4 5 6 7 80 1 2 3 4 5 6 7 8
Period, sec
Scenario spectra
Baker and Yang, 2008
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(b) Peak building responses
Wall shears and moments
0 0.5 1.0B5
L1
L6
L11
L17
L22
L27
L32
L37
L42
Wall Shear
FloorNumber
0
Wall Moment
0 0.5 1.00 0.5 1.0B5
L1
L6
L11
L17
L22
L27
L32
L37
L42
Wall Shear
FloorNumber
0
Wall Moment
0 0.5 1.0
DBE
CMS, T2
CMS, T1
CMS, T3
DBE
CMS, T2
CMS, T1
CMS, T3
DBE
CMS, T2
CMS, T1
CMS, T3
Baker and Yang, 2008
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Design values?
BASE
13th
ROOF
(a) Building elevation (b) Summary of results
Roofdrift, ft Wallbaseshear, k
Wallmoment at13th floor,1000 x k-ft
Minimum
MaximumMean (m)
m +c.o.v.
Nonlinearstatic
2.1
6.74.25.40.23
7600
2970015500222000.43
5500
513
108090010900.21
760
after Maffei
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a design philosophy in rare earthquake ground shaking
there should be no more than a 50% chancethat demands will exceed capacities forductile failure modes, and
the chance of experiencing a nonductilefailure mode should be less.
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Structural wall tests
Berkeley and PCA tests ca 1970s and 1980sCTL 1980
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Flexural assessment
+2.0%
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 200 400 600 800 1000 1200
Distance from the left end [mm]
strains
Test Results+2.0%
Wallace 2007
Fiber model
T i l fl
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Typical flexure
verification
Core walltension strains
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Shear-compression failure
Corley, Fiorato, Oesterle, ACI SP 72, 1981CTL 1980
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Design for brittle failure modes Design demands shall consider
dispersion of calculated responses. Design strengths shall be based on
specified materials properties with
strength reduction factors per the code.
R =capacityQ =demand
Y =R - Q
Y
Y
Y = R - Q
Frequency
P[(Y = R - Q) < 0]
= shaded area
YY
Y
Y = R - Q
Frequency
P[(Y = R - Q) < 0]
= shaded area
R =capacityQ =demand
Y =R - Q
Y
Y
Y = R - Q
Frequency
P[(Y = R - Q) < 0]
= shaded area
YY
Y
Y = R - Q
Frequency
P[(Y = R - Q) < 0]
= shaded area
Y
Y
Y = R - Q
Frequency
P[(Y = R - Q) < 0]
= shaded area
YY
Y
Y = R - Q
Frequency
P[(Y = R - Q) < 0]
= shaded area
Vn Vu
mean +
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Outrigger Forces1.2D + 1.6L
Moreactions
(L reduced)
moments(L not reduced)
Gravity
1.0D + 0.1L
MoM
o
/4
Seismic
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Calculated outrigger axial forces
0 100 200 300 400 500 600 700 800 900B5
1
6
11
17
22
27
32
37
42
axial force [kips]
Floor
number[-]
Mean
Mean + stddata
Yang, 2008
Slab-wall connection
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Slab-wall connection
performance
Klemencic, Frye, Hurtado, Moehle, PCI, 2006
i kConfine diagonals
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Link
beams
g
Confine section
ACI 318, 2008
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Diagonally reinforced link beams
-4.32 -2.16 0 2.16 4.32Relative Displacement (in)
-200
-100
0
100
200
LateralLoad(k)
-0.12 -0.06 0 0.06 0.12
Drift (% Rotation)
ln/h = 2.4
Diagonal (B2)
Full (B1)
Rotation = 0.06
Wallace, 2007
B kli t i d b d
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Buckling-restrained braces and
steel plate shear walls
LA Live!, Los Angeles
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WAMU Center, Seattle
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One Rincon Hill, San Francisco
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One Rincon Hill, San Francisco
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One Rincon Hill, San Francisco
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February 2005
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February 2005
WAMU Center, Seattle
March 2005
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March 2005
WAMU Center, Seattle
April 2005
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April 2005
WAMU Center, Seattle
May 2005
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May 2005
WAMU Center, Seattle
J une 2005
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J une 2005
WAMU Center, Seattle
J uly 2005
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J uly 2005
WAMU Center, Seattle
August 2005
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August 2005
WAMU Center, Seattle
September 2005
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September 2005
WAMU Center, Seattle
October 2005
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October 2005
WAMU Center, Seattle
November 2005
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November 2005
WAMU Center, Seattle
December 2005
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December 2005
WAMU Center, Seattle
J anuary 2006
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J anuary 2006
WAMU Center, Seattle
February 2006
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February 2006
WAMU Center, Seattle
March 2006
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WAMU Center, Seattle
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LA Convention Center Park 5th Pershing Square
76 stories
11 ft/story
2000 Third, Seattle
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Millennium Tower, San Francisco
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LA Center, Los Angeles
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Grand Avenue, Los Angeles
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Summary New generation of tall
buildings Performance-based design
Opportunities andchallenges
Grand Avenue, Los Angeles