The Research Of The Dynamic Response Of The Rail System And Viaduct By Moving Load

In the dynamic system of track and interaction between the vehicle and track , it is convenient to consider six sub-systems: the vehicle, wheel /rail contact and representation of excitation, the rail, the fastening system, the sleeper, the sleeper support (including ballast and substrate ). For the complexion of interaction of every component and the material non-linear, there is no perfect model of the rail system until now. In the present, the models used widely are two kinds:The continuous model. The continuous model is supported by "smearing out "the discrete support along the track. Giving a continuous viscoelastic foundation and a continuous layer represent sleepers. This continuous layer can model the sleepers as rigid bodies or as beams with distributed mass and stiffness. The continuous model are valid only for calculation of the track's dynamic response at frequencies lower than 500 Hz for vertical excitation .Another is the discrete model. Considering the interaction between the sleeper and the sleeper support, it can be modeled as discrete model. A discrete model appears more representative of reality for the majority of track.The major research of this paper is that:1, It is analyze the displacement response of the elastic-foundation beam by the static loads and the moving loads, the dynamic response of Winkler beam, analyze the influence of the sleeper in the dynamic response of the rail system. And compare the result with the experiment formulation. It is concluded that the continuous model only fit for the lower moving velocity of loads. In the higher velocity, especially in the critical velocity, the continuous model is invalidity.2, In this paper, assume that the track and wheels are ideally smooth and no carriage or wheel-axle bending vibrations occur. Invoke the basic hypothesis of the Bernoulli-Euler theory of beams: namely, that plane cross-sections initially perpendicular to the axis during bending. It is bring forward the discrete model of Euler beam. The moving loads and reaction caused by rail are discrete by stepwise constant functions in time domain. The calculation of load effects is simply, but thecalculation of the effect of react force is complicated. The calculation of the vibration caused by react force is discussed in detail, and compared with continuous model. The proposed method is applied to the viduct system.3 The interaction of the rail system 's component is discussed furthermore. The two-dimension model is put up. the result is compared with Euler beam modulus, satisfied results has got. By the experimental formulation, the one-dimension model is put up. The result is compared with the two-dimension modulus, satisfied results has got.