1. PEER 2002 PEER Annual Meeting Geotechnical Seismic Simulation uAhmed Elgamal uUCSD PEER 2002 Annual Meeting Vision: Professor Steven Kramer (PEER Geotechnical Thrust Area Leader)

2. Humboldt Bay, Middle Channel Bridge 330 meters long, 9-span built in 1972 (seismic retrofit in 95 & 00) Supported on piles in soft soil vulnerable to liquefaction Near active seismic zone with reverse faulting mechanism Instrumented including nearby downhole array Selected in Collaboration with Caltrans Recently: Pat Hipley Keith Porter (PEER) Cliff Roblee Tom Shantz Mark Yashinsky

3. Project Goals Develop a bridge seismic assessment framework based on computational modeling and sound probabilistic analysis Ultimately…, a “Decision Making Tool”: Estimate Maintenance/repair expenses Estimate down-time/reduced capacity Explore Retrofit scenarios Predict Emergency shutdown scenarios

4. Maintenance/repair cost

5. Down-time… Lane closure….Emergency Shutdown (e.g., repair cost or loss of functionality) Professor Joel Conte

6. Finite Element Model Mesh generated using GID ( http://gid.cimne.upc.eshttp://gid.cimne.upc.es Prof. Pedro Arduino http://ce.washington.edu/~geotech/opensees/) Water Table Abutments Structural Joints Liquefaction SSI OpenSees: Professor Greg Fenves Dr. Frank McKenna Dr. Zhaohui Yang, Prof. Joel Conte

7. Abutment Joints: ZeroLength Element with Gap-Hook Material As Built 1/2” Expanded Joint Filler All Around Shear Key Abutment Superstructure Approach Slab Beam Abutment: Quad Elements Finite Element Model Hook Gap ZeroLength Element Gap-Hook Material Force [kips] Prof. Joel Conte

8. Soil Constitutive Model Pressure-dependent multi-surface plasticity model (for gravel, sand, and silt), incorporating liquefaction effects Dr. Zhaohui Yang

9. UC Berkeley Shear Tests: Pestana, Seed, and Kammerer

10. Comparison of Matlock’s (1970) test on soft clay and PySimple1 with the same loading path. Prof. Ross Boulanger SSI

11. Yang, Conte, Zhang

12. clay Sand (Dr=50%) Sand (Dr=80%) Centrifuge model setupSimulated 1D response Simulation of UC Davis Centrifuge Test Kutter, Boulanger, Idriss, and Wilson

13. Current Research: Seismic Hazard Analysis Middle Channel Bridge Dr. Paul Somerville J. Conte Site Specific Eq. motions at 3 Hazard Levels (50%, 10%, and 2%)

14. Plastic Bowl Method Prof. Jacobo Bielak/Prof. Boris Jeremic Current Research: Spatial Definition of Input Excitation SCEC Lateral Boundaries, Base of the Mesh, Transmitting boundary, Wave propagation

15. 4x3 pile model Plastic zone 3D 2D Mesh, Piles, and Abutments Professor Boris Jeremic

16. UC Berkeley Photo Database 100 years “too late” for this Bridge, But just in time for Humboldt Bay. OpenSees