Three-dimensional random vibrations of a high-speed-train–bridge time-varying system with track irregularities are studied in this paper. The rail irregularity is regarded as a random process. By extending the pseudo-excitation method, three kinds of rail irregularity are transformed into a pseudo load vector of the coupled system. A finite element model is used to describe the bridge and a spatial multi-body mass–spring–damping model is adopted to represent a moving railway car. Monte Carlo simulations are implemented to validate the presented method. A detailed case study on the train–bridge coupled system is conducted; it is focused on the effects of three kinds of rail irregularity on the stochastic characteristics of the dynamic responses of the system. The effect of randomness on the level of safety and the riding comfort created by the coupled system are also discussed. The results demonstrate that track irregularities may have a greater impact on the transverse response of the coupled system than on the vertical responses.
Upwarping on the longitudinally coupled prefabricated slab track system caused by the rising temperature is a common distress, which deteriorates the mechanical properties of the coupled slabs and the vertical stability of slabs. The objective of this paper is to quantify the upwarping deformation on the slab subjected to temperature force and to find out the influence of different factors on the upwarping phenomenon of the slabs. An analytical expression is deduced using energy method, and a finite element model is also established to verify the analytical solution's adequacy. The following main findings are drawn: (1) when the amplitude of the initial elastic misalignment is equal to a half of the amplitude of the initial plastic misalignment and the half-wavelength min takes the most unfavorable value, the maximum relative error between the analytical solution and the result in FEM is only 2.64%, which demonstrates that the analytical solution correlates well with the FEM results.(2) min is closely related with . With the increase of , min becomes longer, and the maximum length of the half-wavelength is 7.769 m.(3) When the total amplitude + exaggerates, the slab will be much likely to suffer upwarping.
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