Aerodynamic Stability Analysis of Cable-Stayed Bridges

Cable-stayed bridges under wind loading exhibit dynamic behaviors that depend on the aeroelastic forces and coupling among vibration modes. In particular, the new long-span cable-stayed designs can lead to behaviors highly dependent on the coupling between distinct modal forms of vibration. To broaden the applications of existing analytical models and to examine their possible shortcomings when facing new design concepts, this paper presents a finite-element modal formulation to deal with cable-stayed bridges under laminar wind flow. In this numerical model aeroelastic forces are described as functions of the experimentally obtained flutter derivatives, and coupling among various vibration modes can be easily considered. The derived equations of motions are solved for a numerical example and the results are compared with those obtained from an analytical method in which instability is rationally considered to occur in one particular mode.