California's Bridges: Benicia-Martinez Bridges across the Carquinez Straits (3) by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
1999 (38.043 deg, -122.122 deg.) Benicia-Martinez Bridges
The southbound Benicia Martinez Bridge is composed of seven 528 ft long truss spans. The seismic retrofit would have required extensive work to strengthen the piers and foundations for the resulting large inertia force. The use of 10 ft diameter friction pendulum bearings reduced the earthquake forces being carried by the piers which reduced the cost of the retrofit.
Each bearing was tested on the giant shake table at UC San Diego before it was placed between the superstructure and substructure. Jacking platforms were built onto the top of the piers to allow for easy replacement of bearings, if required after an earthquake.