Research On Aerodynamic Characteristics And Dynamic Response For Vehicle-bridge System Under Cross Wind

In recent years,with the continuous development of high speed railway,the partial cable-stayed bridge has predominated in the present construction due to its beautiful appearance,flexibly settable span,simple construction and reasonable economic performance.However,few partial cable-stayed bridge has been built and little research effort has been developed to the wind-resistant performance and aerodynamic characteristics,since China started late on the partial cable-stayed bridge.This thesis,based on one partial cable-stayed bridge,focuses on the research of the train and bridge system’s aerodynamic performance through the method of 3-D numerical simulation.Furthermore,aerostatic stability of this cable-stayed bridge and bridge dynamic characteristics under the effect of both wind and train are analyzed in this thesis.The main research work and achievements are as follows:1.The 3-D model of a partial cable-stayed bridge is established.Then numerical simulation method of Fluent is adopted to obtain aerostatic coefficients of the bridge in different wind field,and the effects of wind attack angles,wind speed and bridge piers on the aerostatic coefficients of the bridge are analyzed.Furthermore,the finite element software Midas Civil is used to analyze the static wind response of the bridge.Results indicate that when the wind speed reaches 80 meters per second at zero-degree wind attack angle,there is no aerostatic instability and the security of this cable-stayed bridge is guaranteed.2.When trains pass through bridge at high speed,the strong wind caused by trains will have an enormous impact on the flow field characteristics around the bridge.The simplified model of train is selected,with the help of sliding mesh method,simulating a scene that the train is passing through the cable-stayed bridge,and researching the aerodynamic performance of the train and bridge system.Researches show that aerodynamic forces of bridge and train,as well as the aerodynamic moment,change significantly along with the changes in the speed of the train and wind.3.Based on the fundamental theory of multi-body system dynamics,this thesis uses Simpack to establish a simulation model of train,and applies the aerodynamic force and aerodynamic moment,obtained by numerical simulation of Fluent,to the multi-body system dynamics model to get the wheel-rail force.Through the Midas Civil cable-stayed bridge model,the dynamic response of the bridge under the effect of both wind and train is analyzed.It turned out that trains,running through the bridge,have a great influence on the lateral displacement and lateral acceleration of the bridge.