Energy-based analysis of 3D wind-induced-flutter mechanism of a three-tower suspension structure

Abstract

Three-tower suspension bridges have broad application prospects in water-crossing and island-linking projects. The large span, flexibility, and slight rigidity of the central tower of three-tower suspension bridges make them extremely sensitive to wind action and wind-induced flutter, which mechanisms have not been clarified yet. In this paper, the Ma’anshan Yangtze River Bridge in China was taken as an example, and the mechanism of its flutter instability was analyzed from the flutter energy standpoint. Upon formulating the main principles of the three-dimensional (3D) flutter analysis of bridges, the respective method was proposed and applied to the bridge under study, yielding the main vibration modes and the movement decoupling in the time domain analysis. The relevant energy calculation was programmed for the 3D flutter energy analysis of the bridge under study. At the flutter onset, the energies of the torsional and heaving movement systems slightly increased and decreased, respectively, the latter being converted into the former and resulting in its divergence. Aerodynamic damping was the main factor in the system stability, while aerodynamic stiffness slightly influenced its flutter instability pattern.