Dynamic Analysis Of Long-span Bridge Subjected To Wind And Train

With the rapid development of economy, China’s railway ushered in the peakperiod of construction.Also more and more long span railway bridge which loaded in thedeep sea, lake and mountain valleys were constructed.Because of the long-span bridgeswhich are built to span river or sea belong to flexible structure, therefore we shouldconsider the action of wind and train loads on bridge structure to ensure the stability andsafety of bridge structure and train. For the complicated wind vehicle bridge couplingvibration system, it use the method of independent programming with finite elementsoftware to solve the coupling vibration system and obtain the dynamic response of windand train loads on the long span bridge.The main contents of this paper are as following:1. The development situation of domestic and foreign large span bridges aresummarized, including a list of top ten bridges of the different types. A review of theresearch development of wind induced vibration of bridges; aerodynamics study ofvehicle and the vehicle bridge coupling vibration are outlined. Finally, it summarizes theresearch of vehicle bridge system under wind loads and set out the coupled system byregarding the wind, running train and large span bridge. And it introduces the basis ofthis research and research thinking.2. It introducs the wind-vehicle-bridge coupling vibration system. The basiccharacteristics of average and fluctuating components of natural wind are introduced.The vehicle model including the degrees of freedom of body, frame and wheel set isestablished. Briefly summarizes the basic theory of finite element analysis and finiteelement model of the bridge. A dynamic model of wind-train-bridge system isestablished and the relationship between the three aspects is analysised.3. According to the random vibration theory and combined with fluctuatingcharacteristics of natural wind simulated by matlab, the fluctuating wind velocity timecurve is obtained and veritied. According to the creep theory and combined withMATLAB, it takes the electric multiple unit (EMU) of different types driving on thelong span bridges as the load calculated by the interaction between wheel and rail.Compared with experimental results, it verifies the accuracy of the wheel-rail forceprogram.4. Firstly,under no wind loads, it take the wheel rail force input to the finite elementanalysis model of bridge built by Midas and solve the dynamic response of the bridge.Also it verified this kind of method for solving the coupled vibration of vehiclebridge system. Secondly, it take the wind load as an external load input to vehicle bridgesystem and establish the model of wind vehicle bridge system and introduces the solvingmethod for the vibration equations of the system.5.Taking the large span continuous rigid frame bridge, arch bridge and cable-stayedsuspension bridge as an example, the dynamic response of the large span bridges underthe action of wind and running train such as CRH1、CRH2、CRH3、CRH5are calculatedand analyzed. The research content mainly includes self vibration characteristicsanalysis of bridges and dynamic response of bridges under the vehicle speed, windattack angle and wind speed changed, etc.The results show:(a) The wind loads have great influence on the lateral displacement and lateralacceleration of large span bridge and have little effect on the vertical displacement andvertical acceleration;(b) The vertical displacement and vertical acceleration of middle span of long spanbridge increase with the wind loads increased, but the trend of time course curvebasically unchanged;(c) Without wind loads, the displacement and acceleration of long-span bridges hasa certain extent along with the vehicle speed change. But the lateral displacement andlateral acceleration obvious influenced under wind loads.(d) When the vehicle speed, wind speed or the wind attack angle is changed, thedynamic response values of middle span section of long span bridge are larger than theothers.