Seismic control of a single-tower extradosed railway bridge using the E-Shaped steel damping bearing

An extradosed bridge is a hybrid structure that combines the main elements of the classic cable-stayed bridge and continuous girder bridge. Almost all extradosed bridges have the main girder transversely restrained at the pier locations, which may cause extremely large transverse shear force and bending moment on bridge substructures during strong earthquakes. This study thoroughly investigates the efficacy of using the E-shaped steel damping bearing (ESSDB) for lateral seismic control of a prototype extradosed railway bridge. Firstly, high-fidelity finite element models are developed for nonlinear time history analyses for both the ESSDB isolated bridge and two conventional non-isolated configurations (i.e., rigid frame system and continuous system). Parametric sensitivity study is then carried out, which indicates a tendency of decreasing transverse deck displacements and increasing pier base transverse forces with the increase of the ESSDB yield force. The optimal ESSDB yield force is thus selected mainly based on a tradeoff between maximizing the structural force reduction and limiting the deformation demand of the ESSDB. Finally, through detailed comparisons of bridge seismic responses with the two non-isolated cases, it shows that the ESSDB can significantly reduce the transverse seismic force demands in bridge substructures, at a cost of a moderate increase in superstructure displacements and formation of permanent inelastic deformation in the ESSDB. It is concluded that the ESSDB can provide a simple and efficient solution to the transverse seismic control of the extradosed railway bridge.