Vehicle-bridge Coupling And Seismic Response Analysis Of Long-span Low-tower Cable-stayed Bridge

Low-pylon cable-stayed bridge is a type of composite system bridge between continuous beam and cable-stayed bridge.In the past 20 years,it has been widely used in bridge construction at home and abroad.The study of its dynamic response under various external loads has important theoretical and practical significance in deepening the cognition of the dynamic characteristics of the bridge,ensuring the safety of the bridge and vehicles and improving the bridge design level.Panzhihua jinsha river low-pylon cable-stayed bridge is the longest double-line railway low-pylon cable-stayed bridge under construction in China.It adopts the structural form of beam tower consolidation,beam pier separation,and support under the beam.In this paper,the bridge is used as the research object,the finite element analysis software ANSYS and multirigid-body dynamics software UM(Universal machine)are used to analysis respectively the modal analyses,a variety of dynamic response of a moving train load condition analysis,"CRH2" vehicle-bridge under different speed and load of car coupling analysis and time history response analysis under seismic load and train operation in encountered some special working condition,and the dynamic response of the key parts of the index and the safety of the train itself index is evaluated.In addition,the influence of the swing radius and friction coefficient on the seismic performance of the bridge is studied.According to the research,the dynamic results of this bridge meet the requirements of the code.In the first 10 order vibration modes,transverse vibration modes account for the majority.Different driving modes have a great influence on the dynamic response of the bridge,and the acceleration response of the key parts of the two-lane pair traveling in the same direction is more complex.With the increase of speed and load,the dynamic response of the bridge and the unsafety of the train are on the rise.Under the action of el-centro seismic waves,the displacement results of jinsha river low-tower cable-stayed bridge conform to the symmetry rule of the bridge on the whole.The change of the rotational radius and friction coefficient of the friction pendulum bearing will lead to the change of the stiffness of the bearing before and after yielding,affect the deformation of the bearing and the transfer of inertia force between the pier beam,and then affect the displacement and internal force of the key parts of the main beam.When the seismic force and the moving load act together,there is a certain coupling relationship between the two forces.For the change trend of the mid-span displacement and the cable force of the cable,the moving load is the main one;for the change trend of the acceleration and the displacement of the tower top,the seismic load is the main one.