Dynamics of weakly coupled beam structures subjected to moving loads with application to railway bridges

This contribution presents the results of a fundamental study on the dynamic response behavior of railway bridges consisting of a series of weakly coupled beams subjected to moving loads. First, the impact of coupling on the natural frequencies and eigenfunctions of structures comprising two or three beams is examined. Next, the critical speeds for resonance and cancellation are determined for a single load moving at a constant speed. The maximum response acceleration for these structures under a group of moving loads at equidistant intervals is computed separately for each span and presented as a function of the ratio of load spacing to beam length, the non-dimensional speed and the coupling parameter. Finally, the dimensionless response acceleration induced by the universal trains of the HSLM-A load model for high-speed trains is calculated. The results demonstrate that certain parameter combinations can result in significantly greater response acceleration than in the single-span beam, due to weak coupling.