Research On Vehicle-bridge System Coupled Vibration Of Steel Box And Steel Truss Composite Girder Cable-stayed Bridge With Three Towers

Abstract:The steel girder cable-stayed bridge has two common forms of main girder:steel box girder and steel truss girder. The combination of these two forms ensures not only the integral stiffness of the girder but also the more convenient and quicker railway construction. With high load and soft structure, the cable-stayed train bridge shows significant problem in vehicle-bridge coupled vibration, thus requiring higher stiffness. The determination of stiffness parameters is a significant part of cable-stayed bridge design and is of particular importance to the cable-stayed bridge with new form of girder. The work of this paper is based on the National Natural Science Foundation project of "wind tunnel test research of aerodynamic characteristics and anti-capsizing performance of high-speed railway vehicle-bridge system (51178471)". Combined with a steel box and steel truss girder cable-stayed bridge with three towers, the major work and results are as follows:(1) With the consideration of the structural features of the steel box and steel truss composite girder cable-stayed bridge with three towers, the simulative dynamic analysis and elaborate calculation model of the vehicle-bridge system is established. Then it calculates and analyses the dynamic features of the model. The results indicate that the bridge fundamental frequency is transverse vibration mode, with intense vibration modality and high coupling.(2) With the use of the above elaborate calculation model, the simulative dynamic calculation and research is carried on the original design of. The result shows that the train has enough safety and comfort when it crosses the bridge at design speed.(3) A detailed research on the effects of stiffness parameters such as beam width, girder height, stiffness of stable cable, stiffness of middle tower and secondary dead load, on the natural vibration and the vehicle-bridge dynamic response varying pattern of Dongting Lake steel box and steel truss composite girder cable-stayed bridge is carried out. The results show that the increase of the width of girder can significantly increase lateral vibration frequency and reduce the transverse vibration response of the bridge. The increase of the height of girder, the stiffness of the middle tower and the stable cable can significantly reduce the vertical vibration response of the bridge. The effects of secondary dead load on lateral and vertical stiffness of the bridge are not obvious, indicating the low sensitivity of secondary dead load.