Dynamic Responses Of Coupled Train, Automobile And Bridge System Under Strong Wind And Analysis Of Running Safety And Riding Comfort Of Vehicles

The study on coupled wind-train-automobile-bridge system has great significance for running safety and riding comfort of vehicles, design and maintenance of bridge. The main contents and achievements of this paper are as following:1. Aerodynamic model of train is proposed. The train is idealized as a combination of a number of rigid bodies connected by a series of springs and dampers. The wind acting on the train composed of the wind generated by relative movement of train and atmosphere, mean wind and fluctuating wind. Aerodynamic forces expressed as aerodynamic coefficients and relative wind speed for train function. Aerodynamic coefficients consider the impact of bridge and wind yaw angle.2. Two types of aerodynamic models of automobile are presented. One is aerodynamic model of contact points with sideslip, which is used to analysis the coupled system under sudden wind. The other is aerodynamic model of contact points without sideslip, which can calculate the coupled system under normal wind. They are different in forces between car and road, model degree numbers and used conditions. The aerodynamic forces are calculated by the same way of the train model.3. Railway-bridge, highway-Bridge and highway-railway-bridge are modeled respectively. The bridge is represented by the conventional finite elements with geometric nonlinearity. Aerodynamic forces consist of mean wind, buffeting and self-excited aerodynamic forces. Aerodynamic coefficients of the bridge are different with vehicles or without vehicles. Three-dimensional fluctuating wind fields considering different heights are simulated.4. This paper presents an efficient and practical framework for dynamic analysis of coupled wind, train, automobile and bridge system in time domain. This method is easy to consider any general types of automobiles and trains, running modes, road roughness, track roughness, different speed of vehicles, different speed of natural wind and so on. As two types of new numerical algorithms, "difference-uncoupled method" and "predictor-implicit integration method" are proposed respectively, this can perfectly solve the equation. In each integration step, the solution need not iterate, the matrixes of equation need not reassembled.5. The associated computer program named as VSI are accordingly developed. The program can be used to study Wind-induced vibration of bridge, Dynamic behaviors of bridge, wind-train-bridge interaction, wind-car-bridge interaction, wind-road vehicle-train-bridge interaction and so on. Residual monitoring is used to ensure the accuracy of the solution. And safety monitoring is used to monitor the condition of vehicles.6. Dynamic performances of coupled wind-train-simply bridge system are calculated. The indictors of safety and riding comfort are established. The effects of the speed of the train and running model are discussed under windless. Meanwhile, dynamic behaviors of the bridge and running safety and comfort of trains are estimated according to relative indictors of safety and riding comfort. The effects of speed of the train, speed of the natural wind, rail roughness, aerodynamic characters of the train and aerodynamic characters of the bridge are studied. Finally dynamic performances of trains are calculated under different wind velocity. Then critical speeds of the train under any natural wind are fixed.7. Dynamic performances of coupled wind-automobile-continuous bridge are analyzed. First the VSI program is proved reliable by comparing with the calculation results of reliable software. Then the effects of the speed of the train and running model are discussed with windless. Meanwhile, the indictors of safety and riding comfort of the car are established. Dynamic performances, the safety and riding comfort of cars at any speed are studied. And critical speeds of natural wind are fixed. Finally the effects of the wind and vehicles to dynamic performances of bridge are analysis.8. Dynamic performances of coupled wind-automobile-train-bridge are studied. Chao-Tian-Men-bridge is modeled. Vibration characteristics are calculated by Ansys program and VSI program, and showed the same results. The mutual influences among automobiles, trains and bridges under natural wind are discussed. Wind induced vibration of highway-railway-bridge and dynamic performances of rail-bridge, wind-rail-bridge, automobile-bridge, wind-automobile-bridge, automobile-rail-bridge and wind-automobile-rail-bridge are calculated. The results show that automobiles have little influences on dynamic performances of trains, while, trains affect dynamic performances of automobile in lateral direction under natural wind. Wind, automobiles and trains have influences on the bridge.