Aerodynamic study of slotted box girder using computational fluid dynamics

Joint study with Mitsui Engineering & Shipbuilding Co. Ltd. and Public Works Research Institute, etc. has been focused on aerodynamics of the slotted box girder to ensure wind-resistance characteristics for achieving a super-long span bridge of which central span is over 2800 m. The section is made of a slotted box girder, and a permeability fence is arranged on the top of the guard rail as windshield barrier. As a new approach, three-dimensional static analysis of unsteady flow was carried out by finite element technique with LES turbulence model. The designed section was confirmed in actual scale model to have enough resistance to the wind velocity over 80 m/s by means of the countermeasures. In this study, a very fine mesh model was adopted to represent the real section in detail including complicated wind counter measures. The result of the analysis with modified attack angles has proved a good agreement with that of the wind tunnel test in terms of three components of the static aerodynamic wind forces. The flow patterns are visualized by these analyses and have verified the mechanism between the modified attack angles and their resultant aerodynamics.