Consistent Numerical Model for Wind Buffeting Analysis of Long-Span Bridges

Abstract

Summary The buffeting analysis of bridge structures considers both, the aero-elastic behaviour of the structure and the wind loading correlation. This calculation is commonly performed in the modal space and in the frequency domain. It includes aerodynamic damping and stiffness effects due to the structural movement caused by the wind flow. The aero-elastic parameters of the cross-sections (drag, lift, pitching moment and derivatives, usually determined in wind tunnel tests) are the basis of this type of analysis. The non-linear dependency of these parameters on the wind direction must be accounted for during both, the static mean-wind and the buffeting analysis. The wind profile is characterised by the mean wind velocity and the fluctuation (turbulence) velocity where the height profile of the wind velocity is assumed to follow an exponential expression. The stochastic nature of wind loading (longitudinal, vertical and lateral components of the fluctuation velocity) is accounted for by using power spectra in the frequency domain. The spatial distribution (coherence) of the wind loading is commonly determined from an exponential decay function of the frequency and the geometry of the structure. This paper reports on performing a buffeting analysis in a commercial bridge design computer program. The implementation of the buffeting analysis in a bridge design program means that all non-linear effects that may have taken place prior to the wind event can be included in the calculation. This allows a complete global analysis of bridge structures and has been applied to the buffeting analysis of the Rach Mieu Bridge in Vietnam and the Shenzhen Western Corridor as well as the Stonecutters Bridge in Hong Kong that serve as application examples in this paper.