Numerical Investigation of the Vibration Performance of Elastically Supported Bridges Under a Moving Vehicle Load Based on Impact Factor

Bridge support boundaries usually change in an operating environment, such as the deterioration of elastic constraints caused by bearing damage and pier scouring. The dynamic response of a bridge under a moving vehicle load may be amplified due to changes in the support boundaries. In this paper, the vibration characteristics of elastically supported bridges under moving vehicle loads are investigated through a numerical model accompanied by a dynamic impact factor (IM) to estimate the amplification effect. A beam elastically supported at both ends and a simplified two-degree-of-freedom moving spring mass system are used to construct a vehicle–bridge interaction model, followed using the road surface condition (RSC) as an input and the Newmark-beta method to solve the interaction equation to obtain the dynamic response of the bridge. Finally, the impact factor is calculated, and a case study including bridge and vehicle parameters is carried out to evaluate the impact of the boundary deterioration on the dynamic response of the bridge. The results show that the dynamic response of the elastically supported bridge increases with decreasing bridge span and vehicle weight, as well as the deterioration of the RSC and support boundary, when the degradation of the support boundary is serious, the IM may exceed 1.0 even if the RSC is in good condition, which suggests that maintaining the flatness of the bridge deck and the integrity of the support boundaries can reduce the impact of the bridge dynamic effect.