Multiple Earthquake Effects on Vulnerability of Horizontally Curved RC Bridges

Abstract

ABSTRACT Bridges subjected to mainshock–aftershock sequences experience significant damage as a result of repeated shaking. Therefore, neglecting the effects of multiple earthquakes may lead to a considerable underestimation of bridges seismic vulnerability. The uncertainties in modeling bridge structural systems as well as the representation of seismic loads significantly affect the bridge vulnerability, especially for horizontally curved bridges, where complex loading conditions exist. In this study, fragility curves for horizontally curved bridges are developed for both mainshock only and mainshock–aftershock sequence cases. The seismic response of a typical four-span horizontally curved reinforcement concrete box-girder bridge is evaluated using the cloud analysis method and the effects of uncertainties on the probability of failure of the bridge components are examined and quantified using the Latin hypercube sampling technique. The results from this investigation indicate that considering the mainshock only could significantly underestimate the damage level even by around 50% and that incorporating uncertainties could change the bridge capacity by more than 45% of its estimated value.