Equivalent Models of an Infinite Track for Frequency and Time Domain Analyses

Purpose Railway track models for the study of train-track interaction are generally based on beam structures on viscoelastic foundations and infinite-length track models are typically used when the track is supposed to be unbounded. However, when non-linear dynamic features or discontinuities of track properties should be considered, it is necessary to perform time domain numerical integration using a finite-length one. This work proposes an approach to develop finite-length models so that the computed results of the frequency and time domain train-track interaction analyses have negligible differences compared to those computed by an infinite-length model, by assigning proper values to the crucial model parameters. Particular attention is paid to obtain equivalent rail responses to stationary and moving point loads. Methods The track model consists of an Euler-Bernoulli beam supported by a viscoelastic foundation. The beam is formulated by both analytical and Finite Element models. The solution techniques adopted include the exact solution of differential equation, the numerical computation based on the Finite Element model, and the modal superposition approach. Proper values of the beam parameters are firstly determined through frequency domain analysis. Then the parameter values of the beam formulation techniques and solution techniques are determined with time domain analysis. Results and Conclusions Frequency responses and responses to moving load excitations are computed. The developed finite-length models lead to negligible difference in terms of frequency responses and responses to low-frequency moving loads. For high-frequency moving loads the responses are highly similar. Consequently, the developed finite-length track models are regarded as equivalent to the infinite-length one for both frequency and time domain analyses.