2. Computational Modeling in Geotechnical Engineering By
Siavash Zamiran, Ph.D., P.E.
Senior Project Engineer, Marino Engineering Associates, Inc.
Adjunct Faculty, St. Louis University
Engineering Mechanics Institute Conference 2019
California Institute of Technology, Pasadena, CA
June 2019

3. Part 2B – Dynamic Modeling

4. Outline Earthquake modeling using fully dynamic analysis
Seismic considerations
Practical example: Seismic analysis of the cantilever retaining wall

5. Outline Earthquake modeling using fully dynamic analysis
Seismic considerations
Practical example: Seismic analysis of the cantilever retaining wall

6. Pseudo-Static vs. Dynamic Analysis
Seismic coefficients for pseudostatic slope analysis, Cristiano Melo and Sunil Sharma

7. Pseudo-Static Analysis

8. Dynamic Analysis

9. Dynamic Analysis, Important points
Loading
Boundary condition
Damping

10. Boundary Conditions and Loading

11. Boundary Conditions

12. Boundary Conditions

13. Rigid Base VS Compliant Base

14. Normal and Shear Stress

15. Baseline Correction

16. Damping

17. Local Damping
set dyn damp local ; = pi * 0.05

18. Rayleigh Damping
set dy_damp rayl zmin fmin stiffness
mass

19. Hysteretic Damping

20. Hardin/Drnevich Hysteretic Damping
Hardin/Drnevich model – hardin
initial damp hyst hardin .005

21. Outline Earthquake modeling using fully dynamic analysis
Seismic considerations
Practical example: Seismic analysis of the cantilever retaining wall

22. Codes for Dynamic Analysis
config dyn
;---static analysis
set dyn off
;---dynamic analysis
set dyn on
ini xdisp 0 ydisp 0 xvel 0 yvel 0
;---history monitoring
hist reset
his sxx i 71 j 35
his xdisp i 72 j 34
his xvel i 72 j 34
his xacc i 43 j 2
his dytime
;---damping
set dy_damp rayl stiffness
initial damp hyst hardin .005
;set dyn damp local ; = pi * 0.05
;----dynamic analysis setting
set corr_ffrot on ;base rotation prevention
app ff
set dytime 0.0
set large
;set multi on
set step

23. Codes for Dynamic Analysis
;---solving
solve dytime=eq_time
;---history reading
;set hisfile test1.his
;his write 105 vs 108 skip 100
;----earthquake loading FISH program
def eqset_1
eq_time=39.88
pgmulti=1.0
c_s1=(shear_a/dens_a)^0.5
multi_sxy1=-0.01*(dens_a)*(c_s1)*pgmulti
end
eqset_1
;---compliant base
hist 1000 read M7_Loma_Prieta.his
hist write table 100
apply sxy multi_sxy1 hist table 100 from 1,1 to 30,1
apply xquiet yquiet from 1,1 to 30,1

24. Codes for Dynamic Analysis