Study On Dynamic Performance Of The Steel Bridges Under The Influence Of Large Axle Load Heavy Haul Train

Railway heavy-load transportation in large and long distance freight has become one of the main development direction of railway transportation in the world. Along with the construction of passenger dedicated line network of our country put into use, to reform the proper strengthening existing railways, heavy-load transportation development, improve the ability of freight, will be one of the main development direction of railway transportation in China. Along with the load increase, the interaction of vehicle and bridge problem is particularly prominent, Bridge structure has the characteristics of big span and small stiffness. Under dynamic impact, its vibration effect is obvious, and it will impact the vehicle in turn, affect the safety and steadiness of train running, so the relation forms the vehicle-bridge coupling vibration. This issue of vehicle-bridge coupling vibration is extremely complicated because the interactional course is random, variational as the time and nonlinear in structure and material.In this article, a new vehicle-bridge model is constructed which is more practical. Based on the model established on 27 DOF the equation of motion of vehicle and the dynamics finite element equation of the bridge structure are set up. Then, we set up the dynamic formula of the whole system adding in wheel-track force. Provided that track irregularity is a random process, a series of sample is simulated instead of the actual process and we must assure that it is long enough in time domain. Thus, we input the sample to the vehicle-bridge system and use the compiler computational procedure to obtain the result of dynamic response through the numerical integration method. The mass matrix, damp matrix and rigidity matrix in the dynamic formula of the vehicle-bridge system change frequently as the time, in other words, they are all temporal function. In addition, the form of matrixes also change accordingly, which result in that at every new time, so matrix must be re-formed. This reflects the essential characteristics of vehicle-bridge coupling vibration, but also reflects the complexity of such problems.Many valuable conclusions can be drawed through the analyse of dynamic response under the different conditions in time domain, they can be used in the design of bridge structure and to simulate the actual locomotory course on suppositional bridge and estimate the security. The advance and limit of speed when vehicle runs on bridge can also be directed by these conclusions. In addition, they can be used to direct the control of vibration, estimate of dynamic capability and reinforce of bridge structure. In addition, the calculated theoretical data presented herein can provide reliable references for vibration control and dynamic performance analysis and reinforcement problems of the bridge structure, which can provide reference for the safe operation of trains and the comfort of ride.