Experimental study on suppressing vortex-induced vibration of a long-span bridge by installing the wavy railings

It is known that vortex shedding behind bluff bodies can be suppressed by introducing some three-dimensional geometric disturbance. Therefore, a new passive control device named wavy railings is proposed to mitigate the vortex-induced-vibration (VIV) of a single box section bridge. The wavy railing is composed of vertical posts and wavy crossbars, which can provide three-dimensional perturbation to the flow field and then lead to the development of a three-dimensional free shear layer which does not roll up into a vortex street and hence suppress the VIV. In this study, the control effects of the wavy railings on mitigating VIV are investigated through wind tunnel tests. The results reveal that when the wavelength of the wavy bar is 0.5H or 1H (H is the height of the bridge deck), both vertical and torsional VIV can be completely suppressed, and the upper surface edge is the optimal installation position.