Seismic Isolation of Benicia-Martinez Bridge

The devastating earthquakes in California, Japan, Turkey, Greece and Taiwan, and the resulting loss of lives and property, have made it apparent that it is necessary to protect bridges from earthquake damage. The uninterrupted operation of bridges immediately after an earthquake is vital for rescue operations, as well as to limit the economic losses of a region. Design methods that rely on structure ductility to absorb earthquake movements do so at the expense of damage to the bridge structure. These damaged bridges may not be usable after an earthquake, and the time and costs to implement repairs can be extensive. In contrast, seismic isolation design relies on the ductility of the isolation devices to absorb or reduce the earthquake energy transmitted to the structure, and thereby protects the structure from damage and preserves its functionality. The application of Friction Pendulum seismic isolation for the seismic retrofit of the Benicia-Martinez Toll Bridge located near San Francisco, California is presented. It is one of the largest bridges to date to undertake a seismic isolation retrofit, and uses the largest seismic isolation bearings ever manufactured. Results of tests of full-size prototype bearings at the new Seismic Response Modification Device Test Facility at the University of California in San Diego are also presented.