Author(s)

S.E. Thomasen

Abstract

The most common historic bridge type in California is the concrete bridge. These concrete bridges have a distinct local imprint, the technology is innovative and the designers have placed great emphasis on the aesthetics. The most graceful are the concrete arch bridges, often located in the rugged wilderness of the State.' Many of these historic concrete bridges show sign of deterioration due to corrosion or excessive cracking. They do not meet the current requirement for traffic loading and they no longer have an acceptable safety margin against seismic failure. The present technology for the preservation and seismic strengthening of historic concrete arch bridges in California is demonstrated in case studies. These include the Donner Summit Bridge, a fixed type open spandrel arch bridge in the Sierra Nevada, the Colorado Street B

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