Stress and acceleration analysis of coupled vehicle and long-span bridge systems using the mode superposition method

Dynamic stress and acceleration response analysis of coupled vehicle-bridge systems is important for both bridge safety and vehicle comfort assessment. Nevertheless, a complex finite element model with many degrees of freedom (DOFs) is often required for stress analysis of coupled vehicle and long-span bridge systems, and the mode superposition method may have to be applied to manage the problem. A general procedure for stress and acceleration response analysis of coupled vehicle and long-span bridge systems using the mode superposition method is therefore presented in this paper. The resonance conditions of simple beams under a sequence of equidistant moving loads of identical weights are first analyzed, and the number of vibration modes required in the stress analysis is then discussed. The Tsing Ma Bridge in Hong Kong is selected as a case study to demonstrate the importance of the number of vibration modes involved in the stress analysis based on a comparison with measured stress responses. The acceleration responses of both the railway vehicles and the Tsing Ma Bridge are finally used to evaluate the in-vehicle passenger comfort and track stability. The results demonstrate that the proposed general procedure is feasible and efficient.