Effects of Inhomogeneous Wind Fields on the Aerostatic Stability of a Long-Span Cable-Stayed Bridge Located in a Mountain-Gorge Terrain

This study investigates the effects of inhomogeneous wind fields on the aerostatic stability of a long-span cable-stayed bridge, which straddles a typical mountain-gorge terrain. Inhomogeneous wind fields, with featured wind speeds and wind attack angles, along the bridge's main beam were firstly analyzed by using the computational fluid dynamics (CFD) approach. Then, a nonlinear methodology was implemented by adopting the ANSYS parametric design language (APDL) technology to analyze the aerostatic stability of long-span bridge under inhomogeneous wind speeds and inhomogeneous wind attack angles. The effects of inhomogeneous wind attack angles, inhomogeneous wind speeds, and both inhomogeneous wind speeds and inhomogeneous wind attack angles on the bridge's aerostatic stability were comprehensively investigated. The aerostatic deformation of the bridge's main beam and the variation of the cable's axial force were also analyzed. The results show that the critical wind speed of the aerostatic instability under inhomogeneous wind attack angles is much smaller than that under homogeneous ones, and the performance of the aerostatic stability under inhomogeneous wind attack angles mainly depends on the peak wind attack angle rather than the average value of those inhomogeneous wind attack angles along the main beam. The wind-load effects acting on the main beam under inhomogeneous wind speeds are larger than those under homogeneous ones, and the critical wind speed of the aerostatic instability under inhomogeneous wind speeds is mainly determined by both the average and peak wind speeds along the main beam. The shapes of vertical displacements and torsion angles along the main beam are mainly dominated by the wind attack angles. However, the lateral displacements along the main beam are relatively independent, where the shapes are generally symmetrical to the midspan line and the values are mainly dominated by the oncoming wind speeds.