Project Title/ID Number Examining Site Response issues for NGA—2M01
Start/End Dates 8/1/03 – 3/1/04
Project Leader Z. L. Wang (Geomatrix/I)
Team Members C.C. Chin (Geomatrix/I), Maury Power (Geomatrix/I)

F=faculty; GS=graduate student; US=undergraduate student; PD=post-doc; I=industrial collaborator; O=other

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1. Project Goals/Objectives:

The issues to be examined in the study:

  1. RASCAL against SHAKE (equivalent-linear soil model);
  2. SHAKE against non-linear codes (SUMDES and D-MOD2);
  3. Selection of typical dynamic properties and profiles for the analyses;
  4. Selection of typical ground motion sets.

2. Role of this project in supporting PEER’s mission (vision):

This project will support the NGA project (lifeline) in resolving the modeling issues that will be used to develop the site amplification functions needed by NGA attenuation relationship developers in their regression analyses of empirical ground motion data.

3. Methodology Employed:

RASCAL uses random vibration theory, SHAKE uses frequency domain solutions; non-linear codes use time domain integration. Results are compared at average level from multi-input motions (30 records).

For non-linear analyses, input motions were also scaled to different levels to examine the evolution of soil non-linearity.

4. Brief Description of past year’s accomplishments (Year 6) & more detail on expected Year 7 accomplishments:

  1. Typical sites, geophysical measurements, dynamic soil properties were reviewed and selected;
  2. Two sets of earthquake records were selected, spectral matched and used in the study (30 records for each of two magnitudes);
  3. RASCAL and SHAKE results were compared for two magnitudes and three soil profiles in terms of amplification functions and response spectra;
  4. Two non-linear codes (SUMDES and D-MOD2) were revised (SUMDES) and evaluated (D-MOD2);
  5. Non-linear results were computed using the two codes for selected records and compared with SHAKE at different scaled input levels.

5. Other Similar Work Being Conducted Within and Outside PEER and How This Project Differs:


6. Plans for Year 8 if project is expected to be continued:

Continue and complete comparisons between SHAKE and non-linear codes.

7. Describe any actual instances where you are aware your results have been used in industry:

In Geomatrix, non-linear (as well as equivalent linear) response and deformation (including liquefaction) analyses are our routine project works. A number of projects have been completed using the model (Wang et al., 1990) that is the core model of SUMDES, but through a two- dimensional program FLAC. These projects were performed for clients including PG&E, EBMUD, ARMY of CORPS and so on.

8. Expected Milestones & Deliverables:

Not determined yet.

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