Dynamic analysis of railway bridges with random vertical rail irregularities

The effects of vertical rail irregularities on both bridge and vehicle vibrations are investigated by applying a recently proposed substructure approach. Specifically, the train-railbridge system is idealized as the assemblage of three substructures. Vertical track irregularities are modeled as stationary and ergodic Gaussian random processes in space, characterized by an assigned Power Spectral Density function. Then, the irregularities represent a source of stochastic excitation and the dynamic response of each substructure is described by a random process in time. In the present study, a second-order analysis of bridge and vehicle random vibrations is carried out. For this purpose, Monte Carlo simulation technique is applied to the set of second-order ordinary differential equations with time-dependent coefficients and stochastic excitation governing the dynamic response of the coupled train-rail-bridge system.