The dynamic response of a simply supported double-beam system under moving loads was studied. First, in order to reduce the difficulty of solving the equation, a finite sin-Fourier transform was used to transform the infinite-degree-of-freedom double-beam system into a superimposed two-degrees-of-freedom system. Second, Duhamel’s integral was used to obtain the analytical expression of Fourier amplitude spectrum function considering the initial conditions. Finally, based on finite sin-Fourier inverse transform, the analytical expression of dynamic response of a simply supported double-beam system under moving loads was deduced. The dynamic response under successive moving loads was calculated by the analytical method and the general FEM software ANSYS. The analysis results show that the analytical method calculation results are consistent with ANSYS’ calculation, thus validating the analytical calculation method. The simply supported double-beam system had multiple critical speeds, and the flexural rigidity significantly affected both peak vertical displacement and critical speed.

Rail irregularity is the leading cause of enhancing train-track coupling vibration and, therefore, should be studied in detail for safety requirements. In this study, the differences between existing rail irregularities without being subjected to an earthquake between different countries were first studied. Results show that existing power spectrum density and time-domain displacement samples of rail irregularities in the American code are the largest, while the irregularities of the Germany railway are higher than those of China in a specific range of rail wavelengths. Afterward, the effects of earthquake intensity, soil site, and duration on the rail irregularity of a Chinese typical high-speed railway bridge were investigated. For this purpose, a finite element model was established and validated by the shaking table test of a 1/12-scaled high-speed railway bridge experimental specimen. The calculation results indicated that the influences of earthquakes on the rail alignment irregularity were evident.

This study proposed a dynamic characteristic analytical method (ANM) of a composite box girder bridge with corrugated steel web (CBGCSW) by completely considering the impact of shear lag effect and accordion effect of corrugated steel webs. Based on energy principles and variational principles, a vibration differential equation and the natural boundary conditions of a CBGCSW were developed. The analytical calculation formula for solving the vibration differential equation was then obtained. The results calculated using the ANM agreed well with previous experimental results, which validated the correctness of ANM. To demonstrate the superiority of the ANM, the vibration frequencies of several abstract CBGCSWs with varying ratios of span–width, obtained using the elementary beam theory (EBT) and the finite element method (FEM), were compared with those obtained by ANM. The efficacy of the ANM was verified and some meaningful conclusions were drawn which are helpful to relevant engineering design, such as the observation that a higher natural vibration frequency and smaller span–width ratio significantly magnified the shear lag effect of CBGCSW. The first five-order natural vibration frequencies of the CBGCSW were significantly lower than those of the composite box girder bridge with general steel web (CBGGSW), which indicates that the impact of the accordion effect is significant.

An efficient model of high-speed railway simply supported bridge with China Railway Track Structure II (CRTS II) ballastless track structure, setup on ANSYS platform, is proposed in this article. The goal is to improve the low computational efficiency and reduce the high computer memory consumption caused by complex bridge models of numerous spans. Programming language and modeling procedures are utilized to ensure that all spans in the proposed model of a large multispan simply supported railway bridge have consistent boundary conditions. Hence, only the middle span is simulated. The comparison of the first longitudinal vibration modes and first natural frequencies of the proposed model and the conventional simply supported bridge model preliminarily validates the feasibility of the model. It also confirms the range of the span number that the proposed model can simulate with accuracy. Taking into account eight different seismic excitations, the results further prove that the proposed model can significantly improve the computational efficiency of the seismic analyses, and can decrease the modeling complexity and calculation time cost without loss of accuracy. The design verification of three different heights of pier groups and the consideration of nonlinear springs enables the proposed model to be utilized in a wide range of applications. As a conclusion, for seismic simulation of high-speed railway simply supported bridges, the proposed model is a reliable alternative for practical engineering simulation.