oasys siren. bedrock soil surface output motion f = f input motion displacement
TRANSCRIPT
Oasys SIREN
Oasys SIREN
Bedrock
Soil Surface
Output motion
F
= F
Input motion
Displacement
Response spectrum
The use of SIREN in the Seismic Design of Stonecutters Bridge
Jack Pappin
Site Response
Liquefaction
Foundation Design
Bedrock
?
Site Response
Mexico City ground conditions
Ground conditions
SIREN - input parameters
• Soil profile
• Density
• Small strain shear modulus G0 g
• G/G with shear strain amplitude
• Input time history – selected to match target bedrock outcrop response from the seismic hazard assessment
Geophysical methods for G0
Down hole insitu test
G0 = VS2
Down hole shear wave testing
Time
Sig
nal
s re
ceiv
ed b
y o
rth
og
on
al s
enso
rs
Shear wave arrival through the ground
Reverse polarity signals generated by hitting beam from opposite directions
P waves or S waves travelling through casing or grout column
Interpretation of Down-hole Seismic Survey
Gsec
G0
1
010.0001 0.001 0.01 0.1 10
Cyclic shear strain (%)
15
0
3050
100PI = 200
OCR = 1 - 15
Variation of G/G0 with shear strain amplitude
Bedrock
Soil Surface
Output motion
F
= F
Input motion
Displacement
Oasys SIREN
CalculatedSite response effects
120 year Velocity Response Spectrum - 5% damping
0.001
0.010
0.100
1.000
0.01 0.10 1.00 10.00
Period (sec)
Ve
loc
ity
(m
/s)
Serviceability
2400 year Velocity Response Spectrum - 5% damping
0.001
0.010
0.100
1.000
0.01 0.10 1.00 10.00
Period (sec)
Ve
loc
ity
(m
/s)
CalculatedSite response effects
Ultimate
6000 year Velocity Response Spectrum - 5% damping
0.001
0.010
0.100
1.000
0.01 0.10 1.00 10.00
Period (sec)
Ve
loc
ity
(m
/s)
CalculatedSite response effects
Structural IntegrityLimit State - SILS
Liquefaction
Philippines 1989
Liquefaction
Philippines 1989
Liquefaction
Standard method of assessing the likelihood
500 10 20 30
0.2
40
0.1
0.3
0.4
0.5
Corrected SPT N value (N1)
Ave
rage
pea
k sh
ear
stre
ss /
vert
ical
effe
ctiv
e st
ress Percent fines (%)
35 15 <5
No Liquefaction
Liquefaction
0
Note: figure applies for a magnitude 7.5 earthquake
FromSIREN
Liquefaction
Predicted likelihood of liquefaction
0
5
10
15
20
25
30
35
40
45
50
0.00 0.10 0.20 0.30 0.40 0.50
CRRM=7.5
De
pth
CRRM=7.5
CSRM
Liquefaction
0
5
10
15
20
25
30
35
40
45
50
0.00 0.10 0.20 0.30 0.40 0.50
CRRM=7.5
De
pth
CRRM=7.5
CSRM
No Liquefaction
0
5
10
15
20
25
30
35
40
45
50
0.00 0.10 0.20 0.30 0.40 0.50
CRRM=7.5
De
pth
CRRM=7.5
CSRM
No Liquefaction
Serviceability SILSUltimate
Bedrock
CDG
Alluvium
Fill
500 250
Bending Moment (kNM)
0 5 10 15
Horizontal displacement (mm)
Soil displacement from SIREN
Pile displacement
100 : 30combination rule
Foundation design - Lateral Loads on Piles
Large Diameter Bored Piles Pile Caps
Pile group modelling
.0 100.0 200.0 300.0
X [m]Scale x 1:1395 y 1:1395
-40.00
-30.00
-20.00
-10.00
.0
10.00
20.00
Y [m
]
Cumulative Graphical Output
Scale factor: 1
et-r11 Event 1 Run 2 Increment 1 18:13 11-06-04
-50.00 50.00 150.0 250.0
X [m]Scale x 1:1627 y 1:1627
-40.00
-30.00
-20.00
-10.00
.0
10.00
Y [m
]
Soil Profile
PilesInterface elements
Free field soil lateral
displacement
Acceleration
Bending moments induced in piles
Cumulative Total Stress Component: y
Interval: 20 Scale factor: 0.1
et-r11 Event 1 Run 2 Increment 1 18:13 11-06-04
< 2020 - 4040 - 6060 - 8080 - 100100 - 120
-50.00 50.00 150.0 250.0
X [m]Scale x 1:500 y 1:500
-40.00
-30.00
-20.00
-10.00
.0
10.00
Y [m
]