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Transcript of Self-Centering Damage-Free Seismic- Resistant...
Self-Centering Damage-Free Seismic-
Resistant Structural Systems
Richard Sause
Professor of Structural Engineering, ATLSS Center Director
James M. Ricles
Professor of Structural Engineering, RTMD Facility Director
Ying-Cheng Lin, Dr. David Roke, and Brent Chancellor
ATLSS Center, Lehigh University
The Fourth Kwang-Hua Forum
and Opening Symposium of Tongji Shaking Table Array
Tongji University, Shanghai
December 11, 2011
Introduction: Conventional Earthquake
Design Practice in United States
• Design for “Life Safety” (LS) for “Design Basis Earthquake” (DBE) with ~500yr return period (10% in 50 years).
• We expect (but do not explicitly design for):
– “Immediate Occupancy” (IO) for “Frequently Occurring Earthquake” (FOE) with ~80yr return period.
– “Collapse Prevention” (CP) for the “Maximum Considered Earthquake” (MCE) with ~2500yr return period.
• Results:
– Expect modest to serious damage to a building from earthquake ground motions with relatively short return periods (in the range of ~100yr to ~500yr).
– Costs to repair damage or to demolish and replace damaged building can be significant life-cycle costs.
Introduction: Expected Damage for
Conventional Steel Moment Resisting
Frame after DBE (~500yr return period)
(b)
(a)
Reduced
beam section
steel moment-
resisting
frame
subassembly
at 3% rad
(0.03 rad)
lateral drift
• Damage leads to residual lateral drift.
• Costs to repair damage and residual drift or to demolish damaged buildings can be significant life-cycle costs
Self Centering (SC) Seismic-Resistant
Structural Systems
Discrete structural members are
post-tensioned (PT) to pre-
compress joints.
Gap opening at joints provides
softening of lateral force-drift
behavior without damage to
members.
PT forces close joints and
permanent lateral drift is avoided.
M
Steel SC moment resisting frame (MRF) subassembly at 3% rad drift
Self-Centering (SC) Steel Moment
Resisting Frames (1997-2004)
Garlock, Ricles, Sause (2008) Engineering Structures
Garlock, Sause, Ricles (2007) ASCE Journal of Structural Engineering
Rojas, Ricles, Sause (2005) ASCE Journal of Structural Engineering
Garlock, Ricles, Sause (2005) ASCE Journal of Structural Engineering
Ricles, Sause, Peng, Lu (2002) ASCE Journal of Structural Engineering
Ricles, Sause, Garlock, Zhao (2001) ASCE Journal of Structural Engineering
Little damage with potential for Immediate Occupancy (IO) under DBE
Comparison of Lateral Force-Drift Behavior
• Conventional system softens by inelastic damage to structural members.
• SC system softens by gap opening and reduced contact at joints.
• SC system energy dissipation is designed feature of SC system.
• Two systems have similar initial stiffness.
-600
-400
-200
0
200
400
600
-8 -6 -4 -2 0 2 4 6 8
Displacement, (in)
La
tera
l L
oa
d,
H (
kip
s)
SC System
Conventional System
Self Centering (SC) Precast Concrete Walls
and Moment Resisting Frames (1994-2004)
PRESSS Program:
Perez, Sause, Pessiki (2007) ASCE Journal of Structural Engineering
Perez, Pessiki, Sause (2004) PCI Journal
Kurama, Sause, Pessiki, Lu (2002) ACI Structural Journal
El-Sheikh, Pessiki, Sause, Lu (2000) ACI Structural Journal
Kurama, Sause, Pessiki, Lu (1999) ACI Structural Journal
Self Centering (SC) Precast Concrete Walls
and Moment Resisting Frames (1994-2004)
Gap opening behavior at 3% rad
drift
Little damage with potential for
Immediate Occupancy (IO)
under DBE
PRESSS Program:
Perez, Sause, Pessiki (2007) ASCE Journal of Structural Engineering
Perez, Pessiki, Sause (2004) PCI Journal
Kurama, Sause, Pessiki, Lu (2002) ACI Structural Journal
El-Sheikh, Pessiki, Sause, Lu (2000) ACI Structural Journal
Kurama, Sause, Pessiki, Lu (1999) ACI Structural Journal
-200
-150
-100
-50
0
50
100
150
200
-7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Lateral Drift (%)
Base S
hear
(kip
s)
T3 (Ap = 7.50 in.2)
T5 (Ap = 3.75 in.2)
fpi/fpu = const. Deformation
capacity
controlled by
post-tensioning
and structural
geometry as
well as material
ductility
SC Precast Walls: Deformation Capacity for
Collapse Prevention (CP) under MCE
(~2500yr return period)
3 cycles to 6% rad drift
SC Damage-Free Seismic-Resistant Steel
Frame Systems Project (NEES 2004-2010)
PT Bars
Moment-resisting frame (SC-MRF) systems
Concentrically-braced frame (SC-CBF) systems
SC Damage-Free Seismic-Resistant Steel
Frame Systems Project: SC-MRFs
Performance Objectives:
• Damage free with potential for Immediate
Occupancy (IO) under Design Basis
Earthquake (DBE) with ~500yr return period.
• Avoid significant yielding limit states.
• Collapse Prevention (CP) under the Maximum
Considered Earthquake (MCE) with ~2500yr
return period .
• Avoid local buckling and PT strand yielding.
Performance-Based Seismic Design of
Damage-Free SC-MRFs
Perimeter SC-MRF as
Experimental Substructure
Tributary Gravity Frames,
Seismic Mass, and
Inherent Damping as
Analytical Substructure
Large-Scale Hybrid Simulations on SC-MRF
Earthquake Loading Direction
• Based on 4-story office building on stiff soil site in California
at 0.6 scale
• Numerical integration of equations of motion for coupled
analytical and experimental (laboratory) substructures.
0.6-Scale 2-bay 4-story SC-MRF Experimental Substructure
Large-Scale Hybrid Simulations on SC-MRF
Floor displacements
at each time step
imposed by
actuators. Restoring
forces feed back to
equations of motion.
Matrix of Simulations
Slow
Hybrid
Large-Scale Hybrid Simulations on SC-MRF
DBE (~500yr return period) MCE (~2500yr return period)
DBE-3 Simulation Results
Level qs max (% rad.)
Residual Drift
(% rad.)
RF 3.9 0.008
3F 3.5 0.023
2F 3.5 0.063
1F 2.1 0.074
Experimental Response • No damage in beams and
columns, except for yielding at column base.
• No residual drift: self-centering
0 5 10 15 20-8
-4
0
4
8
12
Time(sec.)
Flr
. D
isl. (
in.)
1F
2F
3F
RF
DBE-3 Floor Displacements and Story Drifts
Large-Scale Hybrid Simulations on SC-MRF
Findings from Large-Scale Hybrid
Simulations on Damage-Free SC-MRF
• Validated the performance-based seismic design procedure.
• SC-WFD beam-to-column connections dissipated energy (friction) while maintaining self-centering.
• Demonstrated that SC-MRF system can be damage free with potential for Immediate Occupancy (IO) performance under DBE (~500 yr return period).
• Showed that damage of SC-MRF system is minimal under MCE (~2500 yr return period) achieving Collapse Prevention (CP) performance .
SC Damage-Free Seismic-Resistant Steel
Frame Systems Project: SC-CBFs
SC-CBF Configurations Studied by
Numerical Simulations
Frame A
PT bars
Frame B
Fg Fg Fg
Fg
Frame C
PT bars
Frame B
Fg Fg
Typical column uplift and
SC-CBF rocking behavior
SC-CBF Configurations Studied by
Numerical Simulations
Frame D
Energy dissipation
through relative
motion between
uplifting SC-CBF
column and gravity
column
Gravity column
(does not uplift)
SC-CBF column
(uplifts as frame rocks)
ED
element
SC-CBF Configurations Studied by
Numerical Simulations
Frame B
Fg Fg
Gravity columns (no uplift)
CBF
column
Optional
ED
element
Lateral load
bearing with
friction
Frame DDF Configuration DDF
Selected for
Experimental Study
Lateral load bearing
with friction
SC-CBF Configurations Studied by
Numerical Simulations
Performance Objectives:
• Damage free with potential for Immediate
Occupancy (IO) under Design Basis
Earthquake (DBE) with ~500yr return period.
• Prevent significant yielding limit states.
• Collapse Prevention (CP) under the Maximum
Considered Earthquake (MCE) with ~2500yr
return period .
• Prevent member failure (buckling and
subsequent fracture).
Probabilistic Performance-Based Seismic
Design of SC-CBFs
Lateral Force
Roof Drift
1
2 3 4
CP Performance
IO Performance
Limit states:
1: Column
decompression
2: PT bar yielding
3: Member yielding
4: Member failure
Median DBE-
level response
Probabilistic Performance-Based
Design (PBD) of SC-CBFs: Criteria
Δgap
• Based on 4-story office building on stiff soil site in California
at 0.6 scale 3 @ 7’-6”
2 @ 9’
Large-Scale Hybrid Simulations on SC-CBF 6
@ 1
8’ =
10
8’
6 @ 18’ = 108’
Tributary Gravity Frames, Seismic Mass, and Inherent Damping as Analytical Substructure
Single SC-CBF with Adjacent Gravity Columns as Experimental Substructure
Elevation of column line with SC-CBF
Plan of Building
PT Anchorage
PT Anchorage
SC-CBF Experimental
Substructure
Ground Motion Selection
# of θr,max θs,max Vb,max θr,max θs,max Vb,max
Hazard Motion Tests (% rad) (% rad) (kN) * * *
DBE Mean 0.880 0.981 1812
MCE Mean 1.467 1.582 2201
DBE cls000 3 0.641 0.720 1240 -0.81 -0.80 -1.04
DBE 5108-090 14 0.827 0.909 1972 -0.18 -0.22 0.29
DBE h-shp270 1 0.912 1.023 2087 0.11 0.13 0.50
DBE arl090 2 1.393 1.513 2023 1.74 1.62 0.38
DBE nr-pel360 1 0.940 1.147 2483 0.20 0.51 1.22
MCE stn110 2 1.622 1.746 2013 0.31 0.32 -0.32
MCE a-tmz270 1 1.120 1.246 2407 -0.69 -0.66 0.35
MCE lp-hda255 3 1.477 1.588 2341 0.02 0.01 0.24
MCE cap000 1 2.068 2.221 2292 1.19 1.26 0.16
MCE h-cpe237 1 1.742 1.832 2556 0.55 0.49 0.61
tak090 2 4.333 4.460 2711 5.68 5.66 0.87
* - Given as a multiplier of the standard deviation above (+) or below (-) the mean
31 intense EQs used in hybrid simulations
For tak90 the maximum roof drift qr,max = 0.0433rads
is 5.68 larger than the mean qr,max = 0.0147rads for the MCE.
Numerical response statistics for 30 ground motions each input level
Simulation: DBE_arl090_01-04-2010
DBE_arl090_01-04-2010: Roof Drift
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
0 5 10 15 20 25
Ro
of D
rift
(%)
Time (s)
TEST
MODEL
DBE_arl090_01-04-2010: OM vs Roof Drift
-15000
-10000
-5000
0
5000
10000
-2.00 -1.50 -1.00 -0.50 0.00 0.50 1.00 1.50
Ove
rtu
rnin
g M
om
en
t (kN
-m)
Roof Drift (%)
TEST
MODEL
Simulation: MCE_tak090_01-13-2010
MCE_tak090_01-13-2010: Roof Drift
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
0 2 4 6 8 10 12 14 16 18 20
Ro
of D
rift
(% r
ad)
Time (s)
TEST
MODEL
μ = 0.65
MCE_tak090: PT Bar Yielding
0 5 10 15 200
300
600
900
1200
So
uth
PT
Bar
Fo
rce
PT
S (
kN
)
0 5 10 15 200
300
600
900
1200
Cen
ter
PT
Bar
Fo
rce
PT
C (
kN
)
0 5 10 15 200
300
600
900
1200
No
rth
PT
Bar
Fo
rce
PT
N (
kN
)
Time (sec)
North PT Bars
Time (sec)
PT
Ba
r F
orc
e (
kN
)
Post-MCE Aftershock with Small PT Bar
Force from Yielding during MCE
- 1.5%
- 1.0%
- 0.5%
0.0%
0.5%
1.0%
1.5%
0 2 4 6 8 10
Ro
of
Dri
ft (
% r
ad
)
Time (s)
Original: Response of undamaged frame to 5108-090
Aftershock: Response of frame to 5108-090 with reduced PT bar force due to yielding
SC-CBF after 31 DBE-Level and MCE-
Level Hybrid Simulations
Findings from Large-Scale Hybrid
Simulations on Damage Free SC-CBF
• No damage under any DBE (~500yr.
return period) ground motions.
• No damage under most MCE (~2500yr.
return period) ground motions.
• Some damage to lateral load bearings
under largest MCE.
• PT bars yielded under largest MCE:
– SC-CBF performed well under post-MCE
aftershock.
– SC-CBF self-centers after all initial PT force is
lost due to yielding.
– Re-stressing PT bars can return the SC-CBF
to its initial state.
Lateral load bearing
with friction
Conclusions from SC Damage-Free Seismic-
Resistant Steel Frame Systems Project
• Selected SC-MRF and SC-CBF configurations
performed well.
• Essentially damage free under DBE (~500yr.
return period ) with modest damage under
extreme MCE (~2500yr. return period)
response.
• SC steel systems self-centered under all
earthquake conditions that were studied.
• Seismic performance objectives were met.
Acknowledgement
Project: NEESR-SG: Self-Centering Damage-Free Seismic-Resistant Steel Frame Systems
This material is based on work supported by the
National Science Foundation, Award No. CMS-
0420974, in the George E. Brown, Jr. Network for
Earthquake Engineering Simulation Research
(NEESR) program, and Award No. CMS-0402490
NEES Consortium Operation.
Current Work on Medium-Rise Steel SC-CBFs
4 Story
6 Story
9 Story
12 Story
15 Story
18 Story
Thank you