Parametric study of topographic effect on train-bridge interaction of a continuous rigid frame bridge during earthquakes

The local topography hugely impacts the characteristic of earthquake ground motion, further affecting the seismic response of the train-bridge coupled system. Based on the theory of viscous-spring artificial boundary, an analytical model for a train-bridge system subjected to multi-support seismic excitations considering valley topography is established, by applying the displacement time histories of the seismic ground motion to the bridge supports. The influences of the height-to-width ratio of the valley topography, the shear wave velocity of the site soil, and the incident angle of the seismic wave on the seismic responses and running safety of the train-bridge coupled system are investigated by means of parametric investigations, with a 344 m long bridge subjected to the obliquely incident P-wave taken as a case study. The results from the case study demonstrate that the shear wave velocity of the site soil and the incident angle of the seismic wave affect the seismic responses of the train-bridge coupled system in terms of peak occurrence time. The peak values of seismic responses are mainly influenced by the height-to-width ratio of the valley topography as well as the incident angle of the seismic wave.