Seismic Fragility Analysis of Landscape-Covered Bridge with Consideration of the Bridge–Building Interaction

Abstract

The seismic fragility analysis of a three-span landscape-covered bridge with a continuous rigid frame and a reinforced concrete frame structure is performed using traditional reliability theory. To assess the effect of the upper building structures on the bridge, nonlinear dynamic transient analysis is performed based on the spatial finite element model of the structure. The damage indexes of the pier and the bearing are defined based on the displacement failure criterion. Considering the uncertainties of ground motion and structure material, the fragility curves of piers and bearings are obtained by taking the peak ground acceleration (PGA) as an independent variable. The upper and lower limits of the bridge system fragility curves, including the building structures and excluding building structures, are then obtained using the first-order bound reliability principle. The influence of the upper part of the building structure on the bridge system is analyzed, and the seismic property of the bridge is assessed. Results show that building structures significantly affect the seismic vulnerability of the bridge system, which dramatically increases its probability of undergoing extensive and complete damage.