1. Hashash et al. (2005)1 Youssef Hashash Associate Professor Duhee Park Chi-chin Tsai Post Doctoral Research Associate Graduate Research Assistant University of Illinois at Urbana-Champaign PEER 2G02 Site Response Analysis Code Usage Exercise February 15 2005 meeting

2. Hashash et al. (2005)2 DEEPSOIL - OUTLINE DEEPSOIL brief review Site response analysis exercise  Selection of Vs profile  Selection of nonlinear model properties Selected properties Validation of the selected parameters  Rayleigh Damping parameters  Equivalent linear analysis issues  Analysis results

3. Hashash et al. (2005)3 DEEPSOIL - OVERVIEW 1D site response analysis model  1D Equivalent linear analysis  1D Nonlinear analysis  User Interface

4. Hashash et al. (2005)4 FEATURES - Nonlinear soil model Extended modified hyperbolic model   = shear stress   = shear strain  G mo = initial shear modulus   mo = shear stress at approximately 1% shear strain   r = reference shear strain

5. Hashash et al. (2005)5 G / G max & Confinement Damping & Confinement viscous + hysteretic Reference strain -confining pressure dependent viscous damping -Advanced formulation -confining pressure dependent FEATURES - Nonlinear soil model viscous damping

6. Hashash et al. (2005)6 Site response analysis - Vs profile Treasure Island Gilroy

7. Hashash et al. (2005)7 Selection of nonlinear model properties Question: Main parameters: a) Beta b) s c) Ref. strain Response: All use as curve fitting parameters

8. Hashash et al. (2005)8 Reference Strain: Curve Fitting Parameter Ref. strain Ref. strain = 0.07 Ref. strain = 0.2Ref. strain = 0.01

9. Hashash et al. (2005)9 Selection of properties Nonlinear soil model  Comparison of interpreted curves for Treasure Island / Gilroy and curves derived from DEEPSOIL nonlinear constitutive soil model Question: Guidelines on what constitutes a good fit of the modulus reduction and damping curves? Response: -Visual -Comparison of using eq. linear analyses

10. Hashash et al. (2005)10 Selection of properties – Treasure Island It is incapable of accurately capturing the damping at large strains. The damping is usually overestimated. It is the limitation of modified hyperbolic model

11. Hashash et al. (2005)11 Selection of properties – Gilroy

12. Hashash et al. (2005)12 Selection of properties – Gilroy

13. Hashash et al. (2005)13 Selection of properties – Gilroy

14. Hashash et al. (2005)14 Equivalent linear analysis: saving material properties 3 12 1.Name the material 2.Press “Save Material Data” 3.Check whether the newly saved data is stored in the “Use Saved Material Properties” Box Comment: The analysis result of equivalent analysis is unreasonable Response: This is due to incorrect input file Because nonlinear soil property (shear modulus degradation curve and damping curve) are not saved properly

15. 15 Comment: Blacked out cells Response: We do not have the blacked-out cells in our computers (we have installed the program in various machines). Same for the Flexible and Fixed schemes. Can you please let us know the details of the machine that you are using? Equivalent linear analysis: Blacked-Out Cells

16. Hashash et al. (2005)16 Validating the selected parameters for the nonlinear soil model through equivalent linear analysis Comparison of equivalent linear analyses using a)Reference curves (Discrete points) b) derived from the Nonlinear soil model (Modified hyperbolic model)

17. Hashash et al. (2005)17 Selection of optimum modes for viscous damping formulation Selected modes: 1 st + 8 th modes for all analyses

18. Hashash et al. (2005)18 FEATURES - Visual selection of optimum modes/frequencies for the viscous damping formulation Comment: Guidelines on what should be considered as a good match of the linear time domain and frequency domain linear solutions Response: Generally, the first few modes dominate the response. Match first 5 modes of Fourier Transfer function and response spectra of corresponding periods (visually). We need to think if there is a quantitative way of doing that as well. Comment: A legend should be added to the plot which compares linear time domain and frequency domain solutions. Response: Good suggestion, We will improve it

19. Hashash et al. (2005)19 Outcrop motion vs. within motion If only outcrop motion is available, we need to use elastic base: since outcrop motion doesn't consider soil- rock interaction, we need to use elastic base to account for it. If within motion is available, we need to use rigid base: since within motion already considers soil-rock interaction (within motion is a balance result), we need to use rigid base to avoid accounting for soil-rock interaction twice.

20. Hashash et al. (2005)20 Outcrop motion vs within motion A AA B Outcrop motion=A+A Within motion=A+B The reflection wave of within motion (B) is correlated to the soil properties and rock properties. We can use deconvolution to get within motion from outcrop motion. Outcrop motion doesn't consider soil rock interaction, but within motion does. If bedrock is rigid (or soil is very weak), then reflection wave of within motion B=A. i. e. rigid base motion is identical to outcrop motion. There is no iteration between soil and rock Soil Rock

21. Hashash et al. (2005)21 Verification of methodology Treasure Island profile Linear soil properties Input at bedrock Time domain analysis  Input motion: outcrop motion Input at bedrock+ rigid base Input at bedrock+ elastic base  Input motion: within motion Input at bedrock+ rigid base Input at bedrock+ elastic base Two red case should have identical result

22. Hashash et al. (2005)22 Result of Test II (outcrop motion + elastic base) is equal to (within motion + rigid base)

23. Hashash et al. (2005)23 Result of Test – Comparison of time domain and frequency domain analysis If we follow rules of “outcrop motion + elastic base” and “within motion + rigid base” doing time domain analysis, we can get almost identical result as frequency domain analysis

24. 24 Comment: Maximum of 40 layer output Response The maximum number of layers that can be selected is 30 layers, but it is possible to choose layers deeper than layer 30 for output. We will address it in the manual. Output: number of layers The manual should specify the folder where the file for maximum strain profile is saved. Maximum strain profile file is available at DEEPSOIL/ max_strain.txt

25. Hashash et al. (2005)25 Comparison of equivalent linear and nonlinear analysis-Treasure Island Within motion with elastic base not recommended, “Within” motions is obtained from UCLA Team SHAKE analysis. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.010.1110 Period (sec) Spectral Acceleration (g) Equivalent linear analysis Non-linear: Outcrop motion + elastic base Non-linear: within profile motion + elastic Base Nonlinear: within motion+rigid base UCLA: non-linear, outcrop + elastic base

26. Hashash et al. (2005)26 Comparison of equivalent linear and nonlinear analysis-Treasure Island Within motion with elastic base not recommended

27. Hashash et al. (2005)27 Comparison of equivalent linear and nonlinear analysis-Gilroy2 Within motion with elastic base not recommended 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.010.1110 Period (sec) Spectral Acceleration (g) Equivalent linear analysis (DEEPSOIL) Non-linear: outcrop motion + elastic base Non-linear: within motion + elastic base Non-linear:within motion+rigid base UCLA: outcrop + elastic base

28. Hashash et al. (2005)28 Comparison of equivalent linear and nonlinear analysis-Gilroy2 Within motion with elastic base (Not recommend)