Analysis Of Resonant State Of Bridge Under The Moving Load

When the train passes through the bridge at different speeds,its loading frequency changes naturally.When the load frequency is the same as the natural frequency of the bridge,it will cause strong vibration and resonance.With the rapid development of China’s railway industry,as well as the continuous improvement of train speed,resonance problem is also more and more attention than ever before.In this paper,the vertical vibration analysis model of the simply supported beam under the action of single moving force,equidistant moving load and train load is used to derive the analytical solution of the vibration response of the bridge.Through the vibration response analysis,the resonance problem of the bridge and the vehicle is deeply discussed,and the influence factors of vertical resonance of train-bridge system are analyzed.The main research work and conclusions are as follows:1.The analytic solution of the dynamic displacement and acceleration response of the moving load under the damping condition is deduced.The two resonant responses of the simply supported beam under the action of the moving load column and the critical velocity of the train caused by bridge resonance are analyzed.2.The dynamic simulation calculation program of the moving load bridge process is compiled with MATLAB as the platform.The vibration response of the bridge under the resonance is analyzed,and the amplification mechanism in the bridge resonance project is discussed.3.Based on the typical high-speed railway vehicles and bridges,the influence factors of vertical resonance of axle system are analyzed,and the analysis shows that:(1)There is no resonance phenomenon when the train is traveling at a constant speed which is measured by the length of the bridge vehicle spacing,bogie fixed wheelbase load distance However,the resonance response is obtained under the critical speed of the vehicle when the vehicle length is the load space,which proves that the length of the train is the main influencing factor of axle resonance.(2)The damping of the bridge can effectively reduce the resonance response of the train-bridge system;(3)It is verified that the arrangement of beams with a small amount of different span on the bridge between the long distance of bridge of the same span has little effect on the resonance of the vehicle;(4)The stiffness of the bridge directly affects the natural frequency of the bridge.with the increase of the stiffness of the bridge,the vibration response of the bridge is gradually reduced,and the critical velocity of the bridge is gradually improved.Therefore,in the economic reasonable range to improve the stiffness of the bridge,to avoid the previous several major resonance critical speed appears in the normal operating speed,and reduce the vertical vibration response of the bridge.