Coupling Vibration Of Wind-rail Vehicle-bridge System In Complex Mountainous Terrain

In recent years,high-speed railway has been developing rapidly in China.With the implementation of the western development strategy,several high-speed railway lines are about to be constructed in western China,where is well known of various mountains and gorges.The features of terrain vary in complex mountainous regions,which have undulating hills,deeply-cutting gorges and so on.The complex topographic features lead to complicated air flows,which are greatly different from those of the plain areas.Therefore,the following studies were carried out to investigate the running performances of vehicle in the wind environment of complex mountainous terrain.(1)Refined wind-vehicle-bridge system coupling vibration model is established using the rigid-flexible coupling method.Based on the dynamics of rigid multibody system and characteristics of high-speed train,a multibody model of a four-axle train with 34 degrees-of-freedom was established.According to finite element method and dynamic theory of flexible multibody system,the flexible bridge model were built by importing the bridge finite element model into multibody model as a flexible body,and the comparison analysis of wind-bridge actions were conducted for finite model and flexible model.Based on the theory of coupling analysis system,the coupling actions of vehicle and bridge were conducted by introducing the dummy body in the flexible multibody system.The feasibility of vehicle-bridge system was verified,by comparing both bridge and vehicle dynamic responses using equivalent flexible track method and dummy coupling method.On the basis of the study above,the coupling model of wind-vehicle-bridge system was established,and confirmed through the comparison of the interaction of the sub-system,respectively.(2)With regard to aerodynamic admittances of rail vehicle,section model wind tunnel tests were coducted.Three-component aerodynamic coefficients of vehicle on three typical forms of circuit structure,including embankment,bridge and flat ground,were firstly tested in uniform flow.Aerodynamic forces of vehicle on the three circuit structures and corresponding wind speed were tested simultaneously in the simulated B-type incoming boundary-layer flow for the flat terrain and D-type incoming boundary-layer flow for the mountainous terrain.Furthermore,the drag,lift and moment aerodynamic admittances were analyzed.According to the aerodynamic admittances obtained from the wind tunnel test,the curve fitting of admittances function were conducted.(3)The effects of different curve fitting parameters on time-histories of wind loads were analyzed.By the wind-vehicle-bridge analysis under the quasi-steady assumption,the influences of yaw angle on the dynamic responses of vehicle were studied.The most unfavorable condition was obtained,which is cross wind condition.On this basis,the effects of aerodynamic admittances of rail vehicle on the dynamic responses were investigated,where buffeting loads take full consideration of aerodynamic admittances,longitudinal and vertical fluctuating wind,and the effects of different incoming boundary-layer flows and circuit structures on the vibrations of vehicles were studies.(4)The running safety of vehicle on railway curved bridge under the cross wind were investigated.The factors,such as wind direction,operating speed of vehicle,fluctuating wind and track irregularities,on the dynamic responses of vehicle passing through the railway curved bridge were discussed.Meanwhile,the relative results were compared to the results of vehicle passing through the straight bridge.(5)As for the running performance of vehicle passing through the long-span bridge in the complex mountainous terrain,the vibration features of wind-vehicle-bridge were investigated in consideration of non-uniform wind fields in complex mountainous terrain.In the wind tunnel test of terrain model,the variations of mean wind speed and turbulence intensity along the bridge deck were tested for different wind directions,and the effects of local terrain were investigated as well.Through the variations of mean wind speed from wind tunnel tests,the relative relationship of simulation points can be computed.Furthermore,using spectral representation method,fluctuating wind fields for different mean wind speed distributions were simulated,according to the mean wind speeds,wind spectrums and coherence functions of different simulation points.Aerodynamic coefficients of vehicle and bridge were tested by the section model wind tunnel test.Based on the established wind-vehicle-bridge analysis model,the influences of different wind speed distributions on the dynamic responses of coupling system were analyzed.The effects of operating speed of vehicle and mean wind speed were discussed as well.