The Coupling Vibration Research Of Vehicle-track-bridge System Under Wind Loads

With the development of the high-speed railways,the bridges of the high-speed railway are constructed more and more frequently.In the running domestic high-speed railways,bridges have made up approximately 50 percent now.On the one hand,the increasing vehicle speeds lead to more serious vehicle-track-bridge coupled vibrations,on the other hand,wind load causes wind-induced vibration violently because of the great flexibility of the long span bridges.When applying the two types of loads on system simultaneously,the security of the bridge structure will be influenced more by the interaction of these two loads.To ensure the security of the bridge structure,it is very necessary to study the vehicle-track-bridge coupling vibration under the wind load.Taking a large-span railway bridge on the Yellow River for example,this paper analyzed the dynamic responses of the long-span steel truss bridge under the wind load and the train load.The main research contents are as follows:(1)In order to obtain the basic vibration modals and the periods,the software ABAQUS was used to build the finite element model and the Lanczos method was used to analyze the modals of the bridge.According to the specification of railway bridges and numerical method of static wind load to get the two different static wind loads respectively.And The Kaimal spectrum is programmed by MATLAB to get the fluctuating wind speed field.Then the dynamic responses of the three kinds of working conditions are analyzed: The transverse responses are remarkable under the three conditions.The fluctuating wind load has a great influence in the displacement and acceleration of the bridge structure.The structural vibration response increased with the wind speed.When the 30m/s wind load and fluctuating wind load are applied on the structure simultaneously,the structural vibration responses decrease.(2)The software ABAQUS was used to build vehicle,track and bridge model,two-stage suspension and interaction between bridge and track were simulated by connecting element.And the surface contact was used to simulate interaction between the wheels and track.The initial condition when the train is arriving at the bridge has great influence on the bridge acceleration.As the vehicle speed increases,the acceleration changes unobviously,but because of the bridge-train resonance,the peak of the vertical displacement appears at the speed of 125km/h and the peak of the transverse displacement appears at 150km/h.The stress of the linking members of the bridge structure changes obviously with the increasing vehicle speed.(3)The analysis on the vehicle-track-bridge coupled system under the wind load shows that the wind load has influence on the running train and the vehicle speed which causes the peak value of the bridge transverse and vertical vibration response are all 150km/h.The train operation has little influence on the bridge vibration,so the bridge vibration responses still decrease at the 30km/h wind speed.