Mitigation effect of guide vanes on the vortex-induced vibration of a long-span closed-box girder suspension bridge

This paper investigates the VIV responses and triggering mechanisms of a closed-box girder by wind tunnel experiments and computational fluid dynamics (CFD) simulations. The effects of handrails, gantry rails, and guide vanes (GVs) on the mitigation of VIV are analyzed. The results show that large-scale vortices shed from handrails and gantry rails result in large heaving VIV responses. The torsional VIV occurs due to the alternate vortex shedding in the wake. A handrail with a higher porosity near the upper deck surface is highly effective in suppressing VIV responses, especially for heaving VIV. Gantry rails installed at the medial position of the lower deck surface can mitigate torsional VIV to a large extent. GVs installed inside the gantry rails can mitigate torsional VIV much more significantly than one installed outside. For the girder with high-porosity handrails and GVs installed inside the gantry rails, the large-scale vortices generated by the handrails disappear, and the scale of the vortices induced by the GVs is notably reduced, thereby eliminating the heaving VIVs. Additionally, the vortex scale is reduced in the wake region, while the distance between the girder and vortex shedding increases. This effect significantly reduces torsional VIVs.