Analysis Of Vehicle-Bridge Vibration Under Train Induced Wind And Natural Wind

Three-dimensional flow will be appeared near the front and rear of the high-speed train when it is running on the bridge under the cross wind and train induced wind, also the flowfield near the middle part of the train will be affected at some degree. An analysis model of coupling vibration of vehicle and bridge was established to study the train induced wind influence, in comprehensively considering of cross wind, train induced wind and rail irregularities.In this paper, the main research work is carried out to study this analysis model as follows:1. Steady flowfields around the vehicle and bridge when German high-speed train ICE travelling on the railway bridge were obtained based on MRF(multiple reference frame) method by the commercial computational fluid dynamics(CFD) software FLUENT . The present study shows that the effect of train induced wind to the vehicle-bridge system is mainly revealed in the pushing effect near the front of the train, the dragging effect near the rear of the train, a strong vortex is formed following the train. The train induced wind has more influence on zone near the rear of the train, and has little effect to the flowfield near the middle part of the train. In general,the train induced wind has clear influence on the drag force, lateral force, lift force and yaw moment of the train. The whole effect of the train induced wind makes the train to move up and yaw toward the cross wind direction. The train induced wind has evident infulence on the aerodynamic forces of the bridge near the first and end vehicle.2. The bridge vibration effect to the creepage and the space position of track was considered in three dimensional wheel/rail contact geometry. Also the non-linear Shen-Hedrick-Elkins theory was applied to modify the wheel/rail contact creep-forces.3. The analysis model of the vehicle-bridge coupling vibration was developed by comprehensively considering the cross wind, the train induced wind, rail irregularity. And the wheel/rail contact geometric parameters were accurately calculated at each time step iteration. The new improved iteration convergence criterion is that the absolute space position and contact force are unique in the seperated iterative procedure of the vehicle-bridge system.At the same time, iteration accuracy and integration convergency were controlled using the ratio of residual acceleration norms and acceleration norms of vehicle for computing the vibration of each vehicle at every iteration step.4. A German high speed railway standard simply supported beam bridge was used as an example to study the train induced wind influence on the vehicle-bridge vibration of the simply supported small- and middle-span beam bridge. Also the lateral position time history of the wheel/rail contact on the wheel tread and rail head was investigated. The result shows that the train induced wind has some influence on the vehicle safty and has very little influenc on the bridge vibration.Although the train induced wind has some infulence on the reduction rate for wheel load, the derailment coefficient, and the lateral force of the vehicle.but all vibration index of the vehicle are very small compared to the design index. So we can neglect the train induced wind influence on the coupling vibration of vehicle and simplified bridge.5. Taking the south Yashiro bridge in Japanese Shinkansen Line as an example to study the influence of the train induced wind on the vehicle-bridge vibration of long-span bridge. Also the lateral position time history of the wheel/rail contact on the wheel tread and rail head was investigated. The result shows that the train induced wind has evident influence on the safty of the first and last car,and has little influence on the bridge vibration. The train induced wind obviously increases the reduction rate for wheel load, the derailment coefficient, lateral force for the first and the last car. Increasing the bridge vetical stiffness can obviously decrease the vertical acceration,the vertical Sperling index of the vehicle and the vertical displacement,the veritcal accerlation of the bridge.but has very little effect to the lateral vibration of vehicle and bridge. And this reflects the rather weak coupling property of the vertical and lateral vibration in the vehicle-bridge vibration.