Vortex-induced vibration performance of a cable-stayed bridge with a IT-shaped steel-concrete composite girder and aerodynamic countermeasure research

Vortex-induced vibration (VIV) of a long span cable-stayed bridge with a n-shaped steel-concrete composite girder often occurs at frequent wind speeds. In order to suppress VIV of the girder, the effects of different measures on VIV were studied by using a 1 • 50 scale section model wind tunnel test, including installing lower stabilizer, baffle，apron fairing and the combination of fairing and lower central stabilizer. Tests show that only the combination of the fairing and lower central stabilizer can reduce the vertical and torsional VIV amplitude of the girder by more than 75% under different wind attack angles and 0. 66% damping conditions. On this basis, the height of the fairing vertical plate is increased, and the aerodynamic shape of the combination of the fairing and lower central stabilizer is further improved. The effectiveness of the measure was verified by a 1 • 20 large-scale section model wind tunnel test. Finally, the VIV suppression mechanism of the aerodynamic measure was studied by using computational fluid dynamics. Results show that the combination of the fairing and lower central stabilizer can simultaneously reduce the vortex size on the upper and lower surfaces of the girder and effectively reduce the unsteady aerodynamic force on the girder, thereby suppressing the VIV of the girder. The research results can provide reference for the VIV performance design of the Ft-shaped steel-concrete composite girder of long span cable-stayed bridge. © 2022 Chinese Vibration Engineering Society. All rights reserved.