Investigation on suppressing vortex-induced vibrations of the rectangular steel box girder for railway cable-stayed bridges by installing wind fairings

Abstract

Severe vortex-induced vibrations (VIVs) may be observed in rectangular steel box girders because of their blunt aerodynamic shape. Herein, the VIV performance and suppression countermeasures of a high-speed railway cable-stayed bridge with a rectangular steel box girder (breadth-to-depth ratio of 6.71) are systematically investigated through experimental and numerical methods. Significant VIVs of the original girder were observed in wind tunnel tests. Then, the dynamic mesh technology is employed to investigate the triggering mechanism. After that, seven types wind fairings are designed. And the flow pattern around the fixed girder installed with them are simulated numerically. Results show that the leading-edge vortex and the after-body vortex shedding cause the deck VIV, and the former plays a major role. The leading-edge vortices can be eliminated by the inclined web with a degree as 16° or 23°. The optimal VIV suppression countermeasure of a DOWNWARD quadrilateral wind fairing with a platform is proposed. After installing the optimal countermeasure, the leading-edge vortex on the bottom surface of the deck disappears, and the vortex on the upper surface becomes smaller and is trapped. Finally, the suppression efficiency of some typical wind fairings is verified through wind tunnel tests.