| With the coming of the era of modern high speed railway transportation, the research of vehicle-bridge interaction has been strengthen in the word. In recent years, important achievements have been made, especially in researches of force analysis model, the development of vibration sources and calculation means. A great deal of testing data and simulation-based numerical results show that dynamic vehicles and neighbouring structures are essentially random. However, it is well know that the random vibration analysis of vehicle-bridge coupling system is a very difficult problem. As the fundamental of this problem, the dynamic analysis of bridge subjected to random moving loads is received much attention in rencent years. Unfortunately, the complex and low efficiency of the conventional random vibration approaches has considerably restricted the development of the relevant research work. Some research papers have been published. However, most of these papers used relatively simple bridge models and adopted analytical solution or inefficient numerical method to get stochastic response. In the present thesis, based on the theoretical framework of random vibration, the preudo excitation method is applied in the stochastic dynamic analysis of train-bridge system. Comparisons with the Monte Carlo simulations show the effectiveness and statisfactory accuracy of the proposed method. Some innovative schemes based on the above methodology have been further developed, which can be summarized as follows1. Classical theory about train-bridge coupling systemIn order to find out the phenomenon and mechanism about train-bridge coupling system, the thesis has analyzed several classic theories on the coupling vibration of vehicle-bridge system through calculation and results comparison.2. Non-stationary random vibration of bridges subjected to moving loadsIn the present thesis, a FE bridge model is used. Pseudo-Excitation Method (PEM) is applied to rransform the random surface roughness of the track into the superposition of a series of deterministic pseudo harmonic surface unevenness, which overcome the computation bottleneck. Comparisons with the Monte Carlo simulations show the effectiveness and satisfactory accurary of the proposed method. Stochastic vertical analysis has been done on a simply supported beam and of a four non-uniform span beam. |
