Identification of the Most Fragile Component for a Typical RC Bridge Using Seismic Fragility Curves

This paper identifies the most fragile component of a typical reinforced concrete (RC) continuous girder bridge through the seismic fragility analysis. The typical bridge, Liang-Zi River bridge located in Shandong Province of China, is taken as the case study. The Cloud analysis approach is adopted to construct the probabilistic seismic demand models (PSDMs). Both of the record-to-record uncertainty in ground motions and the structural model uncertainty are considered in the PSDMs by using several approaches such as the selection of real ground motion records from the NGA-West2 database and the Latin Hypercube Sampling (LHS) approach. The damage limit states defined refer to piers and bearings which are commonly regarded as the fragile components. Furthermore, the seismic fragility curves of components and the bridge system are developed. Results show that the middle piers are more fragile than the side piers; the bearings are more fragile than piers; it is different from experiences that the fixed bearings at the top of the middle pier are not always more fragile than sliding bearings at both of the transverse and longitudinal loading conditions.