Fragility analysis of a historical reinforced concrete arch railway bridge

Abstract

In this study, fragility analysis of a reinforced concrete arch railway bridge with a total length of 285 m having seven spans of 35 m, a height of 34 m and 15 ‰ slope were performed. The bridge constructed in 1928 still continues to give service. Because the bridge is located in a seismically active region in the southern part of Turkey and on a road, which is critical and important for national railway transportation, it was aimed to perform a probabilistic seismic assessment of the bridge. For this purpose, firstly, 3D finite-element model of the bridge was generated with the software SAP2000 according to the original constructional drawings. Then, the initial FE model was verified using its natural frequencies and mode shapes obtained from in-situ field acceleration measurements. Nonlinear time-history analyses were performed to obtain the seismic demands for 60 different real earthquake records. Probabilistic seismic demand model (PSDM) was derived to determine relations between engineering demand parameter (EDP) and intensity measure (IM). Lateral displacements of the mid-spans were considered as a damage state for three different service velocities. Finally, fragility curves of the bridge were derived.