Youssef Hashash Associate Professor In collaboration with Duhee Park Post-Doctoral Research Assistant University of Ill

1. Youssef Hashash 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): 249-274. • 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. 611-624. • 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), 185-206. • 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 • Numerical Model • User Interface • 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. Damping & Confinement NL Feature – Soil Model G / Gmax & 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. Target Damping Ratio Feature 2 – Viscous Damping Formulation Fig 3-1 Page 68

10. Target Damping Ratio Feature 2 – Viscous Damping Formulation 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. Target Damping Ratio NL Feature– Viscous Damping Formulation

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 300 m 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: ~88m

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)

34. NL Soil Model Parameters - EPRI

35. NL Soil Model Parameters-Treasure Island

36. NL Soil Model Parameters-Anchorage

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