The Research On Coupled Vibration Of Rail-cum-Road Cable-stayed Bridge With High And Low Towers Under Wind Loads

Long-span bridges are flexible structures that are prone to deformation and vibration under wind loads. In addition to meet the strength, stiffness and stability requirements of bridge structures, we should also ensure that the train-bridge coupled system meets the safety and comfort requirements at a magnitude of fluctuating wind velocity when the train is running on the bridge. The work of this paper is one of the main content of the National Natural Science Foundation project—" wind tunnel test research of aerodynamic characteristics and anti-capsizing performance of high-speed railway vehicle-bridge system(51178471)". Taking Hongyan rail-cum-road cable-stayed bridge which the span arrangement is (90+135+375+120) m with high and low towers as the research subject, this paper analyzes vehicle-bridge coupled vibration of cable-stayed bridge under wind loads.The major work and results are as follows:1. Based on the principle that dynamics total potential energy off elastic system keeps unchanged and the matrix matching principle. Established a spatial vibration analysis vehicle model, the wind-vehicle-bridge vibration equation and the finite element dynamics model of the rail-cum-road cable-stayed bridge with high and low towers.2. Adopted aerostatic coefficients measured by wind tunnel tests, calculated the wind load acting on the bridge and vehicle. Reduced the highway load to the value that is equivalent to the uniform load, substituted into the wind-vehicle-bridge coupling vibration equations, respectively calculated the values of the vibration response of the vehicle-bridge under three kinds of road loads.3. The analysis of the values of the vibration response of the vehicle-bridge under three kinds of road loads at different wind speeds showed that:(1) Lateral wind loads play a decisive role on lateral vibration response of bridge structures, while playing an inapparent role on the vertical vibration response;(2)Imposing road load on bridge has greater impact on maximum vertical vibration displacement and maximum beam end angle of the bridge. While having essentially no effect on both the lateral and vertical vibration acceleration, maximum lateral displacemen of bridge and the vibration response of vehicle;(3) Both the lateral and vertical vibration response of the bridge show only small amplitude fluctuations as the train speed improves under the same wind speed, while the values of the various vibration response of vehicle exhibit an increasing trendency as the speed upgrades;(4) Vehicle-bridge coupled system can meet the requirements of train operation safety and comfort when the wind speed is not greater than25m/s, then the train can pass safely. When wind speed is30m/s, it can’t meet the requirement of safety and it do not allow the train to run on the bridge if no additional appropriate support measures are taken.