Free Vibration Analysis of a Periodic Viaduct Supported by Pile Foundations

Abstract

In this study, a numerical model is developed for the analysis of the free vibration of an open-type periodic structure, namely, a periodic viaduct supported by pile foundations. The viaduct is supposed to be composed of infinite spans, with each span consisting of a pile foundation, a pier, two longitudinal beams (left and right beams), and three linking springs. The boundary-element method (BEM) is used to solve the pile-soil interaction problem first. Based on the developed BEM model for the pile-soil system, the compliances of the pile foundation are obtained. By using the compliances of the pile foundation, the joint conditions at the beam-beam-pier (BBP) junction and the transfer matrix method, the eigenvalue equation for the periodic viaduct is established. Numerical results for the energy bands of the viaduct show that there are three kinds of characteristic waves propagating in the periodic viaduct. The first and second kinds of waves are highly decaying. The third characteristic wave can propagate in pseudopassbands with a small attenuation. Also, it is found that, unlike a closed periodic structure, because of the energy transmission from the viaduct to the half-space soil, all energy bands for the open viaduct considered in this study are complex bands with nonzero imaginary wave numbers.