Control of Vortex-Induced Vibration of a Long-Span Bridge by Inclined Railings

The addition of railings inevitably changes the aerodynamic shape of a main girder, which in turn has a great effect on the vortex-induced vibration (VIV) of a long-span bridge. To ensure the railing has a positive effect, this study presents an inclined railing with improved columns arranged with a spanwise distance of 1-5H (H is the height of the bridge). The design of the improved column is inspired by a passive vortex generator (PVG). The streamwise vortices developed downstream of PVG columns can trigger the three-dimensional instability of a wake, making the shear layer less susceptible to rolling up into mature vortex streets, which are the source of VIV. An experimental study is conducted to compare the influence of traditional and inclined railings on the VIV performance of a closed-box section bridge. It is shown that the addition of a traditional railing deteriorates the VIV performance of the bare girder. However, both vertical and torsional VIVs can be completely suppressed by installing an inclined railing. The results of wake analysis indicate that an inclined railing can greatly decrease the streamwise fluctuation velocity and reduce the spanwise correlation of the streamwise velocity in the wake.