1. Oasys SIREN

2. Oasys SIREN = Displacement Output motion Soil Surface Bedrock
Input motion

3. Response spectrum

4. The use of SIREN in the Seismic Design of Stonecutters Bridge
Jack Pappin
Site Response
Liquefaction
Foundation Design

5. Site Response ?
Bedrock

6. Mexico City ground conditions

8. Ground conditions

9. 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

10. Geophysical methods for G0
G0 = rVS2
Down hole insitu test

11. Down hole shear wave testing

12. Interpretation of Down-hole Seismic Survey
Time
Signals received by orthogonal sensors
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

14. Variation of G/G0 with shear strain amplitude1
Gsec
PI = 200
100 G0 50 30 15
OCR =
0.0001
0.001
0.01
0.1 1 10
Cyclic shear strain (%)

15. G0(ij) = rvs(ij)2 where G0(ij) is the elastic shear modulus
r is the bulk density of soil and
vs(ij) is the shear wave velocity through soil
Vs(vh) v
Bender element (vs(vh))
Bender element (vs(hv))
Bender element (vs(hh))
Bender element probe
Vs(hv)
Vs(hh)
Bender element
Soil triaxial specimen
Bender element embedded in base platen
Bender element probe
Hall-effect gauge (radial)
Hall-effect gauge (axial)

16. Oasys SIREN = Displacement Output motion Soil Surface Bedrock
Input motion

17. Calculated
Site response
effects
Serviceability

18. Calculated
Site response
effects
Ultimate

19. Calculated Site response effects Structural Integrity
Limit State - SILS

20. Liquefaction

21. Liquefaction
Philippines 1989

22. Liquefaction
Philippines 1989

23. Standard method of assessing the likelihood
Liquefaction
Standard method of assessing the likelihood
Percent fines (%)
<5
0.5
Note: figure applies for a magnitude 7.5 earthquake
0.4
Liquefaction
0.3
Average peak shear stress / vertical effective stress
From
SIREN
0.2
No Liquefaction
0.1 10 20 30 40 50
Corrected SPT N value (N1)

24. Predicted likelihood of liquefaction
Serviceability
Ultimate
SILS

25. Foundation design - Lateral Loads on Piles
500
250
Bending Moment (kNM) 5 10 15
Horizontal displacement (mm)
Soil displacement from SIREN
Pile displacement
Fill
Alluvium
100 : 30
combination rule
CDG
Bedrock

26. Large Diameter Bored Piles
Pile Caps

27. Pile group modelling Free field soil lateral displacement Piles
Interface elements
Soil
Profile
Free field
soil lateral displacement
Acceleration

28. Bending moments induced in piles