Seismic performance of the San Francisco Bay Area transportation network bridges

Abstract

The objective of this paper is to present the impact of bridge retrofitting in the San Francisco Bay Area on direct loss reduction. For this purpose, the losses from the characteristic earthquakes on the San Andreas and Hayward faults due to ground shaking, landslide or liquefaction are estimated for pre- and post-retrofitted bridges. Bridge losses are computed using the fragility functions from HAZUS [Earthquake Loss Estimation, Technical Manual, 1999] and the Boore et al. [Seismic Research Letters, 1997, 687(1), 128–154] attenuation relationship for ground motions at bridge sites. Loss from liquefaction and landslides is also estimated using HAZUS. The replacement cost for each bridge is calculated using values obtained from the California Department of Transportation (Caltrans). The loss estimates show that the annual risk reduction due to retrofitting is about 15% for the San Andreas fault and 10% for the Hayward fault events. If all possible events are taken into consideration, these values are expected to further increase, demonstrating the benefit of retrofitting.