Numerical study on the mechanism of torsional flutter for Π-shaped section

Four arrangements about vertical plate on Π-shaped section are investigated. A preliminary numerical study is undertaken to identify the vortex-shedding mechanism around deck based on random discrete vortex method. It can be concluded that the separation bubble generated at the lower windward corner and the main vortex structure developed from the separation bubble and its motion around the lower side of the prototype bridge deck are located at it lower surface and traveling across the lower side of the bridge deck downstream into the wake. The period of vortex shedding at the lower windward corner and development of vortex motion around the lower side of the prototype bridge deck make a direct influence on the value of the work done by the local suction pressure induced by the vortexes. Analysis results reveal that different arrange of vertical plates on Π-shaped section can convert torsional flutter to coupled flutter can increase the critical wind speed for the onset of flutter.