Vortex-Induced Vibration Performance and Control Measures of Wide Twin-Box Girder

In order to study the vortex-induced vibration (VIV) characteristics and control methods of wide twin-box girder bridges, a long-span suspension bridge with twin-box girder and a total girder width of 64.1 m was modeled in a 1∶70 scale ratio and wind tunnel tests for this model were carried out under smooth flow. Firstly, the VIV characteristics of the girder under five attack angles (0°, ± 3°and ± 5°) were studied; secondly, the effects of single aerodynamic measures, including using a horizontal aerodynamic plate, closed central gap, grids and guide plates on overhaul vehicle rail and the effects of the measure combinations were also studied. Finally, the influence of the above aerodynamic measures on the flutter performance of the main girder is examined. The results show that the vertical DOF vortex-induced resonance occurs at all five wind attack angles. The most unfavorable attack angle is –3°, and the maximum vertical vibration amplitude is 0.69 m, which exceeds the limit of the allowable value in Wind-Resistent Design Specification for Highway Bridges by 70%. The combined use of grid and other aerodynamic measures can reduce the VIV amplitude of the main girder by 50.7%–98.6%. However, these control measures reduce the critical flutter wind speed by 6%–15%, which still meets the design requirements.