Dynamic Response of Cable-Stayed Bridges under Moving Loads

A modeling method for cable-stayed bridges with nonlinear cables that is used for the dynamic response under moving loads is discussed in this paper. Individual stay cables are modeled by short catenary cable elements in which the nonlinearity due to large displacements but small deformations and the nonlinearity due to the variations of tension are taken into account. A linear approximate bridge model is used to solve the dynamic response of cable-stayed bridges; the nonlinear contribution of the stay cables is added by means of an iterative procedure. Internal nodes of stay cables are not present in the linear approximate bridge model so that it contains a small number of degrees of freedom (DOF), whereas the nonlinear dynamic response of stay cables is computed at cable level, one at a time, by means of the finite-element method using many internal nodes for each stay cable. An illustrative example demonstrates that the proposed method is very efficient, inexpensive, and capable of exhibiting the resonance of stay cables excited by the bridge deck and towers.