Effects of a Moving Load on a Nonhomogeneous Bridge Beam

The understanding of the dynamic response of a beam under a moving load is an active research area in structural engineering. The aim of this note is to investigate such a response for piecewise constant beams that display wave filtering properties associated with band gaps. The performance of five simply supported nonhomogenous piecewise constant beams under concentrated load traveling at ten different constant speeds was analyzed and compared with that of a simply supported homogenous beam with the same volume. The nonhomogenous beam design and the speed range were based on the band gap theory for which traveling waves in a specific range of frequencies cannot propagate for a given piecewise geometry. The investigation has been carried out through analytical and numerical approaches by implementing equations in a MATLAB script and using the finite elements software, LUSAS, respectively. Factors such as number of vibration modes and damping effect were also considered. It was concluded that i) higher speeds do not necessarily generate a more severe beam response; ii) some of the investigated nonhomogenous beams exhibit good performance for a range of speeds that corresponds to the lower interval of the band gap range.