The role of skew wind on wind-induced effects of a cable-stayed bridge girder: Vortex-induced vibration and coherence mode

This study investigated the vortex-induced vibration (VIV) characteristics and mechanisms of a Π-type girder through wind tunnel test. Initially, a wind tunnel test is performed on a 1:60 scale model of the main bridge section to analyze the VIV characteristics under various wind attack angles and wind skew angles (β). Then, numerical analyses are conducted to investigate the flow field characteristics, surface pressure, and vortex distribution at different β, exploring the mechanisms behind VIV onset. The findings indicated that as β increases, the VIV response of the bridge progressively diminishes, with no significant VIV observed at β = 30°. The VIV response is most pronounced at a −3° wind attack angle, whereas the torsional VIV nearly vanishes at a +3° wind attack angle. At β = 0° and β = 10°, large-scale vortices on the lower part of the bridge are primarily concentrated at the trailing edge; however, at β = 30°, these vortices are focused on the leading edge. In addition, as β increases, the energy of vortex shedding gradually decreases, marked by changes in vortex distribution.