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Geotechnical Seismic Simulation

PEER 2002 Annual Meeting. Geotechnical Seismic Simulation. Ahmed Elgamal UCSD. Vision: Professor Steven Kramer (PEER Geotechnical Thrust Area Leader). Humboldt Bay, Middle Channel Bridge. Selected in Collaboration with Caltrans. Recently: Pat Hipley Keith Porter (PEER) Cliff Roblee

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Geotechnical Seismic Simulation

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

  2. Humboldt Bay, Middle Channel Bridge Selected in Collaboration with Caltrans Recently: Pat Hipley Keith Porter (PEER) Cliff Roblee Tom Shantz Mark Yashinsky • 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

  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 Professor Joel Conte (e.g., repair cost or loss of functionality)

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

  7. Abutment Joints: ZeroLength Element with Gap-Hook Material Gap-Hook Material Finite Element Model Abutment: Quad Elements Gap Beam Force [kips] Hook As Built ZeroLength Element Superstructure Approach Slab Abutment 1/2” Expanded Joint Filler All Around Shear Key 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. SSI Prof. Ross Boulanger Comparison of Matlock’s (1970) test on soft clay and PySimple1 with the same loading path.

  11. Yang, Conte, Zhang

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

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

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

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

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

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