San Francisco - Oakland West Bay Crossing
San Francisco - Oakland, California
California Department of Transportation (Caltrans)
email: brian_maroney @dot.ca.gov
Study completed 1994
Scope of work:
- Criteria development
- Foundation modeling
- Local capacity modeling
- Response analysis
- Vulnerability evaluation
- Retrofit concepts
- Nonlinear seismic analysis
- Seismic vulnerability and retrofit criteria
- Multi-support dynamic analysis
- Coordination of multiple subconsultants
The two-mile-long West Bay Crossing of the San Francisco - Oakland Bay Bridge carries Interstate Highway 80 across San Francisco Bay. OPAC evaluated the tandem suspension bridge for Caltrans to determine its anticipated seismic performance in a major earthquake, and to make recommendations and cost estimates for seismic retrofit measures. The scope of work included the following components:
- Criteria development. Establishment of load and deformation criteria for determining vulnerability.
- Foundation modeling. Soil-Structure Interaction modeling to determine properties and demands.
- Global demand modeling. Dynamic 3-D modeling to capture global and regional inelastic response.
- Local capacity modeling. Computer and manual evaluation of load and deformation capacities.
- Response analysis. Response spectrum and multi-support time history, linear and nonlinear analyses.
- Vulnerability evaluation. Estimation of vulnerability based on capacities, demands, and behavior.
- Retrofit concepts. Identification of retrofit strategy to achieve a higher performance standard.
Final design of retrofit measures was performed by Caltrans, using most elements of the retrofit strategy identified in this evaluation. Retrofit construction was completed in 2004.