Transverse Seismic Pounding Effect and Pounding Reduction of Simply-Supported Girder Bridge for High-Speed Railway

A 32 m standard-span simply-supported girder bridge with 7 spans for high-speed railway was used as a prototype to study the effects of the earthquake-induced transverse pounding, as well as the pounding reduction effects of various isolation devices. The actual force-deformation curves of shear keys were determined experimentally and a finite element model considering pounding was established using SAP2000. On this basis, influences of the rail system, the initial gap between the shear keys and bearing padstones, and the thickness of shear-key plates on seismic responses of the bridge were analyzed. Then, the pounding reduction effects of rubber bumpers, lead rubber bearings (LRBs), friction pendulum bearings (FPBs), high damping rubber bearings (HDRs), and fluid viscous dampers were discussed. The results are as follows: the rail system can significantly alter the distribution of seismic forces between bridge spans. Under excitations of the maximum earthquakes considered, the nonlinear effect of shear keys is significant, with the maximum pounding force of 2.18 MN. For the sample bridge presented in this paper, it is a reasonable configuration to set the initial gap between the pounding members as 3 cm and the thickness of shear-key plates as 32 mm. The seismic isolation devices can improve the seismic performance of the bridge; their pounding reduction effects are affected by spectral characteristics of ground motions as well as their own mechanisms. Among them, the FPB has better applicability and the seismic forces between different spans become more uniform after the installation of FPBs.