Nonstationary random vibration, analysis of coupled vehicle-bridge systems

Purpose - The purpose of this paper is to present a new nonstationary, random vibration method for the analysis of coupled vehicle-bridge systems with vertical track irregularity. Design/methodology/approach - The vehicle is modeled using a two-layer suspension system and hence possesses ten degrees of freedom. The bridge is simulated using a Bernoulli-Euler beam and the longitudinal track irregularity is taken as a uniformly modulated, evolutionary random process that includes phase lags between successive wheels. The pseudo-excitation method (PEM) is extended to include time-dependent systems for the first time, thus making it possible to compute the nonstationary random vibration of coupled vehicle-bridge systems. Additionally, the precise integration method (PIM) is adapted to simulate continuous vehicle force variations in both time and space. Findings - The accuracy and effectiveness of the proposed PEM-PIM method are confirmed by comparisons with Monte Carlo simulations. The influence of vehicle speed and track irregularity on system random responses are evaluated, and it is shown that the first and second derivatives of the track irregularity should not be arbitrarily ignored, as is usually the case. Originality/value - PEM and PIM are relatively new tools for the numerical solution of complicated random vibration problems and direct dynamic analyses. Until now, they have only been applied to time-independent systems. However, it is shown herein that the proposed PEM-PlIM method performs nonstationary random vibration analysis of time-dependent coupled vehicle-bridge systems efficiently and accurately.