Richmond - San Rafael Bridge
San Francisco Bay, California
California Department of Transportation
Evaluation completed 1995
Scope of work:
- Review of seismic evaluation
- Check of structural analysis
- State-of-the-art seismic evaluation
- Dynamic analysis of a large complex structure
- Propagating seismic wave analysis
The Richmond - San Rafael Bridge carries Interstate Highway 880 across the northern end of San Francisco Bay. Originally completed in 1957, the 4.25 mile long crossing consists of 10 distinct structural units: two double deck plate girder units, twin concrete trestle approaches, two cantilever truss units with lightweight concrete decks spanning two navigation channels, and five simple truss units. Foundations consist of steel H-piles, bell-caps, and concrete piers.
Caltrans contracted a seismic evaluation of the bridge as part of its toll bridge retrofit program. Work scope included global and local structural analyses, response spectra and multi-support dynamic seismic analysis, strength and deformation capacity evaluations of components, vulnerability assessment, and retrofit strategy development. OPAC participated in the contract in a review and advisory role, with emphasis on bridge behavior, modeling, and analysis checking.
This evaluation was one stage of a multiple-consultant effort to evaluate seismic vulnerability, develop and design retrofit measures, and strengthen the bridge. Seismic retrofit design and construction were programmed by Caltrans based upon this initial seismic evaluation.