Seismic fragility analysis of sea-crossing continuous rigid frame bridges based on fuzzy failure

Abstract

The bridges play an important transportation hub in the transportation lifeline system. The sea-crossing bridges located in earthquake-prone areas may be subjected to earthquake and wave action during their lifetime. This paper mainly investigates the seismic performance of continuous rigid frame bridges supported by group pile foundations based on the seismic fragility analysis. Based on the OpenSees software, the three-dimensional finite element model of the sea-crossing bridge is developed, where the pile-water interaction and pile-soil interaction are simulated by added mass method and p-y curve method, respectively. The uniform input ground motions are used by applying the displacement of the surface ground motion on all spring supports. Based on the traditional structural seismic vulnerability analysis and introducing the theory of reliability, the damage index is reduced by a half-trapezoidal distribution membership function, and the structural damage boundary is fuzzy analyzed to obtain the fuzzy components. Further, the damage limit about the vulnerability of the full bridge system is discussed. Finally, the influence of wave force on structural seismic vulnerability and the vulnerability of the full bridge model under different earthquake types, such as far-field, near-field pulse, and near-field non-pulse types, are analyzed.