Effect of turbulence intensity on aerodynamic force of bridge girder

Abstract:

Due to the complex profile of a bridge girder with several corners, the flow around its section exhibits obvious flow separation and reattachment phenomena. It is necessary to assess how atmospheric turbulence affects aerodynamic force. A segment model pressure wind tunnel test was carried out, and the mean and fluctuating pressure distributions in a uniform wind field and three grid-generated wind fields were obtained. The changes in the aerodynamic forces were evaluated, and the effects of turbulence on flow separation and reattachment phenomena were analyzed. Results showed that turbulence significantly changed the separation and reattachment characteristics of the section at the leading edge (especially the upper surface at zero and positive attack angles and the lower surface at negative attack angles), which in turn affected the aerodynamic characteristics of the bridge section. As the turbulence intensity increased, the amplitude of the mean pressure coefficient at the separation point near the leading edge increased, while the reattachment point moved upstream. The influence of turbulence intensity on separation and reattachment became more noticeable with the increase in the wind attack angle. The force coefficient was more affected by turbulence intensity at a high attack angle than at a small attack angle, mostly because of the pressure changes at the leading edge.