1. Youssef Hashash In collaboration with Duhee Park
Associate Professor
In collaboration with Duhee Park
Post-Doctoral Research Assistant
University of Illinois at Urbana-Champaign
PEER 2G02 First Meeting
September 21, 2004

2. DEEPSOIL 1-D Site response analysis code
Nonlinear / Equivalent linear analysis
User interface

3. Motivation for Development
Thick soil deposits such as those encountered in the Mississippi Embayment in Mid-America
Sponsored in part by Mid-America Earthquake Center
References:
Park, D. and Y. M. A. Hashash (2004). "Soil damping formulation in nonlinear time domain site response analysis." Journal of Earthquake Engineering 8(2):
Hashash, Y. M. A., and Park, D. (2002). "Viscous damping formulation and high frequency motion propagation in nonlinear site response analysis." Soil Dynamics and Earthquake Engineering, 22(7), pp
Hashash, Y. M. A., and Park, D. (2001). "Non-linear one-dimensional seismic ground motion propagation in the Mississippi embayment." Engineering Geology, 62(1-3),
Park, D. (2003). ESTIMATION OF NON-LINEAR SEISMIC SITE EFFECTS FOR DEEP DEPOSITS OF THE MISSISSIPPI EMBAYMENT. Department of Civil and Environmental Engineering. Urbana, University of Illinois at Urbana-Champaign: 337 p.

4. Outline Features of DEEPSOIL Nonlinear Numerical Model User Interface
Equivalent Linear
Additional Features of the User Interface

5. Nonlinear (NL) Features
Soil Model
Viscous Damping Formulation
Dynamic Integration Scheme
Increased Numerical Accuracy
User Interface

6. NL Feature – Soil Model Extended Modified Hyperbolic Model
Based on Modified Hyperbolic Model (Matasovic, 1993)
Confining pressure dependent
Modified Hyperbolic Model

7. NL Feature – Soil Model
G / Gmax
& Confinement
Damping
& Confinement

8. NL Feature– Viscous Damping Formulation
Viscous damping formulation [C]
Simplified Rayleigh damping formulation
Full Rayleigh damping formulation
Conventional Selection of Frequencies/Modes (CRF)
Proposed Selection (RF)
Extended Rayleigh damping formulation (ERF)

9. Feature 2 – Viscous Damping Formulation
Target Damping Ratio
Fig 3-1 Page 68

10. Feature 2 – Viscous Damping Formulation
Target Damping Ratio
Selection of frequencies/modes for Full Rayleigh damping formulation
CRF (Conventional RF) : fm = 1st mode of soil column, fn=dominant period of input motion
RF (Proposed RF) : fm and fn chosen from transfer function of soil column and frequency content of
input motion  An iterative process

11. NL Feature– Viscous Damping Formulation
Target Damping Ratio

12. Numerical Implementation
Cyclic soil response model
Input ground motion
Multi-degree of freedom
lumped parameter model

13. Nonlinear (NL) Integration Scheme
Newmark Beta Method
(Average acceleration method: =1/4, =1/2
Implicit Method
Unconditionally stable
No numerical damping

14. NL Feature – Viscous Damping Formulation
RF – Conventional Approach
Use first mode of soil column and
a higher mode or predominant
period of ground motion

15. NL Feature – Viscous Damping Formulation
RF/ERF
Proposed Guideline
Use iterative procedure to obtain best match with frequency domain solution
Dependent on soil column
Dependent on input motion
ERF: Computationally expensive

16. NL Feature – Viscous Damping Formulation
Variable [C] Matrix
Updates stiffness in the RF formulation

17. NL Feature – Increased Numerical Accuracy
Fixed Sub-incrementation Scheme: Independent of strain level
Flexible Sub-incrementation Scheme: depends on strain level
Input Motion
Station JMA NS Kobe Earthquake, PGA = 0.82g

18. NL User Interface – Input Soil Profile

19. NL User Interface – Input Soil Profile

20. NL User Interface – Soil Model Parameter Selection

21. NL User Interface – Viscous Damping Formulation
ME Profile
M=8,R=32km Motion

22. NL User Interface – Viscous Damping Formulation

23. NL User Interface – Viscous Damping Formulation

24. NL User Interface – Viscous Damping Formulation

25. NL User Interface – Numerical Accuracy Control

26. NL User Interface – Output

27. Equivalent linear (EQL) Features
3 Types of Complex shear modulus
Frequency independent (Kramer, 1996)
Frequency dependent (Udaka, 1975)
Simplified (Kramer, 1996)
No limitation on
number of layers
number of materials
number of motion data points

28. EQL Features
(SHAKE, use with care)

29. Additional Features

30. Verification of DEEPSOIL
Loma Prieta Earthquake, M = 7.1, October 19, 1989
Significance of viscous damping in DEEPSOIL (Strong Motion & non-linear material)
Soil column: ~88 m

31. Verification of DEEPSOIL
E-W
N-S

32. Nonlinear Soil Model Parameters
No Fixed Parameter
Selected to match various reference dynamic curves (G/Gmax and damping curves)

33. NL Soil Model Parameters – Mississippi Embayment (ME)
ME study ME
EPRI 
1.4
0.85 s
0.8
0.9
(a)
Reference ’ref
0.163
0.07
’ref
0.18 b
0.63
0.4 c
Varies with depth d

34. NL Soil Model Parameters - EPRI
ME study ME
EPRI 
1.4
0.85 s
0.8
0.9
(a)
Reference ’ref
0.163
0.07
’ref
0.18 b
0.63
0.4 c
Varies with depth d

35. NL Soil Model Parameters-Treasure Island
Young Bay Mud
Old
Bay Mud 
0.8
0.9 s
0.7
(a)
Reference ’ref
0.17
0.065
’ref
N/A b
0.0 c
1.5 d

36. NL Soil Model Parameters-Anchorage
Bootlegger clay 
0.7 s
Reference strain
0.05
’ref
N/A b
0.0 c
1.0 d

37. Limitations No Pore pressure generation model
Currently under development
Implementation of a NN based constitutive model

38. Questions?

39. Backup Slides

40. Backup Slides