Vehicle-induced random vibration of railway bridges: a spectral approach

The vibration of railway bridges induced by moving vehicles was conventionally evaluated through time domain simulations, which are computationally expensive in probabilistic analyses that require Monte Carlo simulation. A frequency domain solution to the random vibration of railway bridges is derived in this paper where the random wheel-rail force is represented by its power spectral density. As a frequency domain approach, the proposed method is naturally suitable for the random analysis of the vehicle-induced bridge vibration, and the method is highly efficient since it only involves the Fast Fourier Transform (FFT). Numerical examples showed that the simply supported bridge may resonate in several natural modes due to the coincidence of dominant frequencies of hunting forces to the natural frequencies of the bridge. For long-span bridges with low natural frequencies out of which the dominant hunting frequencies fall, resonances are unlikely to occur.