| ABSTRACT: In the process of train speed-raising in existing railways and the construction of high-speed passenger rail lines in China, the impact of running trains on the bridges is becoming more and more serious, thus, the vibration problem of bridge can not be ignored.As a new material of high intension, great endurance and perfect toughness, the Reactive Powder Concrete (RPC) has a bright future. In 2004, the Ministry of Railways of China promoted to make use of this new technique in engineering, and now a low-height prestressed RPC T-beam has been taken into practice. The RPC railway bridge, which has smaller section and lighter weight, will have an obvious change in its natural frequencies and dynamic responses under train loads. The safety and comfort of vehicle are also affected.In this paper, the vibration equations of the train vehicles are established by the principle of virtual work. The vibration equations of the bridge are formed by the general equations of dynamics. The train and bridge system equations are made up of the train and bridge equations with the method of modal synthesis, according to the relation between the wheel and rail. The equations are solved by the Newmark-βmethod.The natural vibration characteristics of a simple-supported RPC T-beam are calculated with finite element method. The dynamic responses of vehicle and bridge as well as the safety and comfort indices are calculated under different circumstances on the basis of bridge modal information, in which the track irregularity is also taken into consideration. Besides, the response results are estimated by related criterion. From the calculation, it is found that the RPC bridge has good dynamic characteristics. The bridge displacement and acceleration responses are comparatively small and satisfied. The indices for vehicle such as running safety, comfort and stability all meet the relevant criterions.In the end, some conclusions and prospects are proposed.
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