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.