Experimental investigation on vortex-induced vibrations of a triple-box girder with web modification

Abstract

Split type box girder is a recommendable structural style for long-span cable-supported bridges due to its excellent aeroelastic stability. A major issue of this kind of girder is its susceptibility to vortex-induced vibration (VIV), which has not been adequately investigated. This paper presents an experimental study on VIV of a triple-box girder with three different web modifications (namely curved web and linear-type webs with different slopes). Both small- and large-scale sectional models were employed for wind tunnel tests considering the Reynolds number effect. Results indicated that the triple-box girder showed poor VIV performances in both construction and completed phases. Generally, linear-type web was superior to curved web in terms of VIV performance. Increasing the structural damping and turbulence intensity of incoming flow were helpful for VIV mitigation. Geometric profiles and arrangement of appurtenant facilities on the girder have significant effects on the VIV performance. Aerodynamic optimal schemes were proposed for VIV mitigation both in construction and completed phases. Obvious discrepancies in VIV responses were observed between the small- and large-scale tests for several scenarios. Possible factors being responsible for the discrepancies were Reynolds number, turbulence intensity, nonlinearity of model structural damping, blockage ratio and geometric accuracy of the sectional models.