Mechanism of Hanger Oscillation at Suspension Bridges: Buffeting-Induced Resonance

Abstract

This article presents the results of an investigation of the wind-induced resonance of hangers on a long-span suspension bridge. The data from field observations, numerical simulations, and wind tunnel experiments presented in this article show that the hangers experience buffeting-induced resonance oscillations and that the source of the excitation is the buffeting of the main cables to which the hangers are attached. Because of the dense natural frequencies of the main cables and the broad-spectrum structural buffeting that takes place, it appears that these oscillations occur as energy is transferred from the main cables to the hangers. Hence, it is the main cables rather than the hangers that trap energy from the oncoming turbulent wind field. The numerical results presented indicate that the resonance of the hangers could be sensitive to positions along the bridge deck, wind speeds, and damping ratios. This article also includes the results of simplified wind tunnel experiments that verified this kind of resonance, disregarding whether the wind loads developed directly on the hanger.