Vehicle-bridge Coupled Vibration Analysis Of The80m Span Steel-concrete Composite Truss Railway Bridge

Long-span steel-concrete composite truss bridge has a significant advantage on thechoice of structural styles belongs to railroad underbridge, which is double clearance underbridge and construction height of bridge limit. As a new type bridge, it costs appealing design,causes less running noice with larger stiffness.4new type steel-concrete composite trussbridges of80m span are adopted and located on the Xian-pingliang railway line. The structurecomposed0f two pieces of triangular steel truss and a grooved concrete girder has beendesigned and used for the first time in China. The natural vibration characteristics andvehicle-bridge dynamic performance of mentioned bridge is studied in this thesis.Regard the80m span steel-concrete composite truss bridge of the Xian-pingliang railwayin Taiyu as engineering background, a simulated analysis of vehicle-bridge coupled vibrationis carried out in this paper. Two finite element models are established for the80m spansteel-concrete composite trussed girder bridge by Midas and ANSYS. Then the naturalvibration characteristics through calculation are compared and analyzed with the resultpulsation-test. The quality matrix and damping matrix of the mentioned structure, which arefigure out by ANSYS, are input to existed program that should be used to analyzevehicle-bridge coupled vibration, as the initialized data. Then vehicle-bridge dynamicresponse with different speeds and loads is calculated and analyzed. Besides that, theresonance speed is predicted and suggested. Finally by changing stiffness parameters ofsteel-concrete composite truss bridge, such as steel web members, grooved concrete girder,upper chord members. The influences on natural vibration characteristic and vehicle-bridgedynamic response with different Components’ damping are analyzed and studied.Through calculation and analysis, the conclusions of this thesis are as follows. Thelateral stiffness of the80m span steel-concrete composite truss bridge is relatively low. At anyspeed from40to80km/h, the vehicle-bridge dynamic response of the bridge due toheavy-loaded vehicle is all below limits. For different speeds, it can be seen that theresonance speed is about60km/h. Composition is made among the dynamic analysis resultsof the bridge due to heavy-loaded vehicle, unloaded vehicle and passenger train, thederailment coefficient and offload reduction rate of unloaded vehicle are much greater thanheavy-loaded vehicle. In a certain range, increasing the stiffness of grooved concrete girder orsteel web members can effectively reduce the large deflection of bridge, but the stiffness ofupper chord members has not a great impact on vibration and bridge responses.