High-speed Railway Bridge Seismic Dynamic Response Research Based On Track-bridge Interaction

As continuous welded rail(CWR) widely used in high speed railway bridges, it has been necessary to better understand the track-bridge interaction under seismic excitations. In this paper, track-bridge coupling nonlinear finite element analysis model is established, using nonlinear track longitudinal resistance model, considering the ductility and hysteretic property of piers, to analyze the seismic response of the track-bridge-coupling system. Main content of this paper is presented as follows:1. Track-bridge interaction analysis and elastic-plastic time-history dynamic analysis are introduced, mainly focusing on two nonlinear characteristics of the structure:nonlinear track longitudinal resistance and nonlinear plastic hinge in piers. For the typical span arrangement of high speed railway bridges, containing32m simply supported girders and (40+64+40) m continuous beam girder, a track-bridge-coupling nonlinear finite element analysis model is established, adopting ideal elastic-plastic model for track longitudinal resistance, and clough hysteretic model for pier plastic hinge.2. Based on FEM method, the influence of track-bridge interaction on structure under seismic excitations is analyzed. The results show that:①Under low-level earthquake, the structure stays at elastic stage; Under design earthquake, the structure may enter into plastic stage, but the plastic behavior would not be obvious; Under high-level earthquake, the structure obviously shows the ductility characteristics.②For the typical span arrangement, containing simply supported girders and continuous beam girder, track-bridge interaction would result in the structure longitudinal seismic response changes19%～62%, especially for the braking pier of continuous beam girder.3. Based on typical span arrangement of high speed railway bridges, considering pier ductility and hysteretic property, the influence of several parameters on the track-bridge-coupling system is analyzed, including track longitudinal resistance, pier stiffness, pile stiffness and the number of bridge spans. The results show that:through the least square method, the relation between the structure seismic response and the parameters above could be described as exponential function form.