Discrete Vortex Analysis on Suppression Countermeasures against Vortex-Induced Vibration of a Box Girder

This paper focused on improving the aerodynamic characteristic of a box girder against vortex induced vibration. Discrete vortex method was used for the analysis. Two kinds of models were used for the analysis: one was a basic section without appendage, while the other was a modified section with an appendage attached only to the bottom plate. Vertical plate was employed as the appendage. The analysis results showed the plate with a certain height was effective to suppress heaving response, and large plate was unnecessary. The mechanism of suppression was as follows. Secondary vortices were formed on both the front and the rear side of the vertical plate as the girder section vibrates. These vortices produced decreasing separation angle and reattachment of the flow. The effective height of the vertical plate on suppression against vortex induced vibration could be decided to some extent from the analysis results of a fixed section.