Coupled Flutter and Buffeting Analysis of Long-Span Bridges

Abstract

Analytical determination of the flutter and buffeting responses of long-span suspended bridges to wind excitation has predominantly been accomplished by single-mode-based methods. Proclivity towards design and construction of even longer span bridges has elevated the possibility of aerodynamic coupling of the flexural and torsional modes of vibration. A comprehensive, frequency-domain procedure developed to capture this multimode aeroelastic and aerodynamic response is presented in this paper. This new procedure is applied to evaluate the coupled response of a cable-stayed bridge. A quantitative assessment of the modal interactions at flutter and in the buffeting response is made to highlight the presence and effects of modal coupling. The multimode responses are then compared to single-mode and pseudomultimode results. As an extreme example, the bridge deck flutter derivatives were replaced with those of an airfoil to further investigate the ability of this approach to capture aeroelastic and aerodynamic coupling.