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Retirement symposium and celebration of the career of Prof. Anil
K. Chopra
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Effect of live loads on the seismic response of pile-supported
storage
structures
Juan C. Reyes, Universidad de los Andes, Colombia J. Paul Smith,
USA
Oscar A. Ardila, Ingetec , Colombia
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USA Building standards (ASCE 716): 25%? Port standards (POLA,
POLB): 10%? Bridge standards (AASHTO): 0%?
What percentage of quasi-permanent live load should be used as
seismic mass?
INTRODUCTION GM Modeling Parametric S Conclusions
1 Research question
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INTRODUCTION GM
DL = 20 kN/m2 LL = 40 kN/m2 = 2
Modeling Parametric S Conclusions
DL = 7 kN/m2 LL = 12 kN/m2
DL = 6 kN/m2 LL = 7 kN/m2 DL = 4 kN/m2 LL = 5 kN/m2
Pile-supported container yards
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2 Ground motions Operational Level Earthquake (OLE): Mw = 6.0 to
6.9
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00
0.2
0.4
0.6
0.8
1.0
1.2
Pse
udo-
acce
lera
tion
Sa,
g
Natural vibration period T, s
CLE - UHSCLE - MeanOLE - UHSOLE - Meanith Record
i-th Record
CLE
Mean
UHS
OLE
Contingency Level Earthquake (CLE): Mw = 6.7 to 7.1
GM Introduction Modeling Parametric S Conclusions
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3 Modeling
B
c k
H
GM Introduction MODELING Parametric S Conclusions
0510152025303540
-1
-0.5
0
0.5
1
A
g
,g
Time, s
-400
-200
0
200
400
-400
-200
0
200
400
Drift
u
p
, mm
Sliding
u
b
-
u
p
, mm
010203040
-500
-250
0
250
500
Time, s
010203040
Time, s
___
FE Model
_ _ _
Numerical model
0510152025303540
-1
-0.5
0
0.5
1
A
g
,g
Time, s
-400
-200
0
200
400
-400
-200
0
200
400
Drift
u
p
, mm
Sliding
u
b
-
u
p
, mm
010203040
-500
-250
0
250
500
Time, s
010203040
Time, s
___
FE Model
_ _ _
Numerical model
H
k
c
B
(c)
(b)
(a)
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Numerical models
fs
up
Vy oVy
k 0.1k
o = 2
mp mb s, k
c
k
Ag
up
ub
Runge Kutta and ANSYS
GM Introduction MODELING Parametric S Conclusions
o = 2
k
0.1k
fs
oVy
Vy
up
ub
Ag
mp
s, k
up
mb
k
c
-
Scaled experimental model (elastic) Characteristics
GM Introduction MODELING Parametric S Conclusions
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Comparisons for elastic cases
-0.50
-0.25
0
0.25
0.50 0.375
Table Acceleration T
able
Acc
eler
atio
n, g
Record No.6
0 1 2 3 4 5 6 7-20.0
-10.0
0
10.0
20.0 17.32915.784 Platform Drift
Plat
form
Drif
t, m
m
Time, s
Runge-Kutta___Experimental___
= 1.51
0 1 2 3 4 5 6 7-20.0
-10.0
0
10.0
20.0 18.59216.799 Platform Drift
Plat
form
Drif
t, m
m
Time, s
Runge-Kutta___Experimental___
= 1.77
Runge Kutta Experimental
GM Introduction MODELING Parametric S Conclusions
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CASE : = 2.0, Cv = 0.8, R = 1.4, T = 1s
Slid
ing
( ub -
up)
, m
m
Drif
t u p
, m
m
0 5 10 15 20 25 30 35 40-1.0
-0.5
0
0.5
1.0
Ag ,
g
Time, s
(a) (a)
0 10 20 30 40
-500
-250
0
250
500
Time, s0 10 20 30 40
Time, s
ANSYS Runge Kutta
Comparisons for inelastic cases
GM Introduction MODELING Parametric S Conclusions
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4 Parametric study Variables Values Total
T (structural Period) [0.1,0.2, , 2] 20
(friction Coefficient) [0.1, 0.2, , .7] 7
(block-structure mass ratio) [0.5, 1, , 2] 4
R (response modification factor) [Elastic, 2, 3] 3
Records 7 OLE, 7 CLE 14
DDR = Drift for structure with sliding block
Drift for structure with rigidly attached block
Total: 23520 analysis cases
Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
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DDR for various friction coefficients
Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
Structural period T, sec
p ,
0.1
0.2
0.3
0.4
0.5
0.6
0.7
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Effective seismic mass
Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
(a) (b)
mp mb s, k
c
k
Ag
up
ub
mp + mb
k
Ag
up*
c
=
(a) (b)
ub
up*
Ag
k
s, k
Ag
mp
up
mb
mp + mb
k
c
c
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Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
Amax / ( g)
Live
Loa
d as
Iner
tia,
= 2.0
= 1.0
= 1.5
= 0.5
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Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
Mass ratio,
(a) (b)
Comparison with experimental results
Equation
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Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
How about rocking?
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Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
How about rocking?
0.2 0.4 0.6 0.8 10
0.1
0.2
0.3
0.4
Structural period, T, s
Plat
form
Dri
ft, m
Squat Block B/H = 0.82Slender Block B/H = 0.32
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Conclusions GM Introduction PARAMETRIC S Conclusions
Modeling
Multiple-story structures?
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5 Conclusions
CONCLUSIONS GM Introduction Modeling Parametric S
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Thanks for your attention
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