Identification of critical structural modes and flutter derivatives for predicting coupled bridge flutter

This study identifies the control parameters which critically influence the development of inter-modal coupling and the generation of aerodynamic damping, based on closed-form solutions of bimodal coupled analysis of bridge aerolastic system. This information helps in developing a guideline for the selection of most critical structural modes in a coupled flutter analysis and in better interpretation and understanding of the multimode coupled bridge flutter response. Also discussed is the role of each flutter derivative and the potential influence of the self-excited drag force on bridge flutter in light of the flutter features characterized by the rate of change in modal damping with increase in wind velocity, which is also referred to as soft- or hard-type flutter.