Vibration reduction of elastically supported beams under moving loads by tuned mass devices

Abstract

This study is aimed at the physical interpretation of the function of a tuned mass (TM) in suppressing the vibration response of an elastically supported beam to a moving train. The train is simulated as a sequence of moving loads, and the vibration shape of the elastically supported beam is approximated as the combination of a flexural sine mode and a rigid body mode. By distinguishing free vibration from forced vibration, resonance of the beam is identified as the superposition of the free vibrations induced by the moving loads that are in phase. The reverse is also true for the phenomenon of cancellation. Moreover, the mechanism of the TM in reducing the resonant response of the beam to the moving loads can be interpreted using similar concepts. From the parametric study, it is concluded that the use of a mass ratio of 0.01 is most efficient for the TM. To achieve the greatest effect of mitigation, the frequency of the TM should be tuned to that of the elastically supported beam.