Finite element dynamic analysis of beams on non-uniform nonlinear viscoelastic foundations under moving loads

It is well know that constant loads moving with a constant velocity on uniform beams supported by uniform foundations may lead to significantly different dynamic behaviors depending on the velocity magnitude; for some velocity ranges the oscillation amplitudes may become very large, thus endangering the structural and passengers safety. This paper presents a study on the dynamic response of beams on an elastic foundation, subjected to moving loads. The response of the system is studied for three types of mechanical behavior of the foundation: (a) linear elastic (classic Winkler model), (b) nonlinear elastic and (c) bilinear elastic (i.e., with different behavior in tension and compression). Peak velocities are determined for beams with or without damping, on uniform foundations or foundations composed of two sub-domains with different values of stiffness. The effects of the load velocity and foundation stiffness are investigated. In the case of non-uniform linear foundations, a very good agreement is obtained between the results of the model and the analytical results available in the literature. The goal of this study is to generalize, for more realistic foundation behaviors, the analyses obtained by other authors.