Resilient Steel Plate Shear Walls:
Analysis of Performance Using OpenSees
and TeraGrid Resources
Patricia M. Clayton
University of Washington
Jeffrey Berman (PI)
Laura Lowes (Co-PI)
NEES-SG: SPSW Research
Jeff Berman and
Laura Lowes
• Tasks:
Michel Bruneau
Larry Fahnestock
K.C. Tsai
Jeff Dragovich
Rafael Sabelli
Sponsored by NSF through the
George E. Brown NEES Program
– Develop a resilient SPSW
– Develop performance based
design tools for SPSW
– Develop a new model for SPSW
web plates
– Explore the behavior of
coupled SPSWs and develop
design recommendations
What is a Resilient Steel Wall?
• Combines benefits of Steel Plate Shear Walls (SPSWs)
with self-centering technologies
• SPSW provides:
–
–
–
–
–
Ease of construction
High strength and initial stiffness
Ductility
Yielding over many stories
Replaceable energy dissipation elements (steel plates)
• Post-Tensioned (PT) Connection provides:
– Self-centering capabilities
– Quick return to occupancy after earthquake
Conventional SPSW Behavior
• Resists lateral load through development of
Tension Field Action
angle of
inclination
lateral
load
HBE
a
VBE
tensile
stresses
HBE
diagonal
folds
Courtesy of Berman and Bruneau
Conventional SPSW Behavior
• Idealized hysteretic behavior of SPSW with simple
HBE-to-VBE connections:
VSPSW
Unloading
Plate yields
D
Low Stiffness
1st Cycle
2nd Cycle
PT Connection Behavior
• Provides self-centering capabilities
• Connection is allowed to rock about its flanges
• PT remains elastic to provide recentering force
• Requires some energy dissipation
• Examples from previous research:
• Yielding angles (Garlock, 2002)
• Friction devices (Iyama et al., 2009; Kim and Christopoulos, 2008)
Garlock (2002)
Iyama et al. (2009)
PT Connection Behavior
• Nonlinear elastic cyclic behavior of PT connection:
VPT
Connection
Decompression
D
qr
1st Cycle
2nd Cycle
Combined System: Resilient SPSW
VPT
VSPSW
D
D
VR-SPSW
Unloading
Plate yields
Connection
Decompression
Plates Unloaded
Connection
Recompression
D
1st Cycle
2nd Cycle
Performance-Based Design
REPAIR OF
PLATES ONLY
V
V2/50
V10/50 NO REPAIR
V50/50
Vwind
Plate yielding
COLLAPSE
PREVENTION
First occurrence of:
 PT yielding
 Frame yielding
 Residual drift > 0.2%
First occurrence of:
 PT rupture
 Excessive PT yielding
 Excessive frame yielding
 Excessive story drifts
Connection
decompression
D50/50
D10/50
D20/50
D
Prototype Building Designs
• Based on 3- and 9-story
SAC buildings in LA
• Vary number of R-SPSW
bays in building
• 2 design types:
• Plates designed
for V50/50
• Plates designed
for V10/50/R
Analytical Model
• Nonlinear model in OpenSees
• SPSW modeled using strip method:
• Tension-only strips with pinched hysteresis
• Strips oriented in direction of tension field
Analytical Model (cont.)
• PT connection model:
Rocking about HBE flanges
Shear transfer
Compression-only springs
at HBE flanges
Diagonal springs
HBE
VBE
PT tendons
Truss elements with
initial stress (Steel02)
Rigid offsets
Physical Model
Analytical Model
Dynamic Analyses
• Each model subjected to 60 LA SAC ground motions representing
3 seismic hazard levels
• 50% in 50 year
• 10% in 50 year
• 2% in 50 year
• Used OpenSeesMP to run ground motions in parallel on
TeraGrid machines
Using TeraGrid
Batch submission script
#!/bin/bash
#$ -V
#$ -cwd
#$ -N jobName
#$ -o $JOB_NAME.o$JOB_ID
#$ -e $JOB_NAME.err$JOB_ID
#$ -pe 16way 64
#$ -q long
#$ -l h_rt=48:00:00
#$ -M myemail@u.washington.edu
#$ -m be
OpenSeesMP .tcl scripts
Ground acceleration records
Abe
set –x
ibrun $HOME/OpenSeesMP $WORK/OSmodel.tcl
Ranger
Using TeraGrid
Run all models and ground motions simultaneously using OpenSeesMP
Processor = 0
Processor = 1
R-SPSW model
Abe
Processor = n-1
Ranger
Using TeraGrid
All results in the time it takes to
run one ground motion.
OpenSees recorder &
output files
Abe
Ranger
Response History Results
• Example of Response during 2% in 50 year EQ
– System Response
– Connection Response
Response History Results
• Statistical results from all 60 ground motions
• Performance Objectives:
– No plate repair (Story drift < 0.5%) in 50/50
(this example designed using V10/50/R; plates not explicitly designed to remain elastic)
– Recentering (Residual Drift < 0.2%) in 10/50
– Story drift < 2.0% in 10/50 (represents DBE)
– Limited PT, HBE, and VBE yielding in 2/50
All performance objectives met !!!
Comparing Designs
R-SPSW designed using V10/50/R
• Plates designed using reduced
“DBE” forces
R-SPSW designed using V50/50
• Plates designed to remain
elastic in 50% in 50 year EQ
•
•
Larger plate thicknesses & frame members
Improved response
o Recentering at all hazard levels
o Smaller peak drifts
Conclusions
• Preliminary design procedure developed for R-SPSW
• Dynamic analyses show R-SPSW can meet proposed
performance objectives
– including recentering in 10% in 50 year EQ
• Highly nonlinear model  significant computational
effort
• Use of TeraGrid resources reduced computational time
by more than 90%
• Experimental studies on R-SPSW currently taking place
Thank You