Effect Mechanism of Central Slot Width on Vortex-Induced Vibration Characteristics of Streamlined Box Girders

The streamlined box girders with central slots usually have good flutter stability, but the vortex-induced vibration (VIV) performance of such box girders at large angles of attack is not clear. For the streamlined box girder section of a long-span bridge, the flow field characteristics and VIV performances of the box girders with five different central slot widths were analyzed by numerical simulation method. Then the influence law of the central slot width on the VIV performances of box girder at large angles of attack were investigated, and the corresponding aerodynamic mechanisms were discussed systematically according to the changes of static and dynamic flow fields. The results show that the drag coefficient of the closed box girder is always the smallest for the wind attack angles in the range of −10°~10°, while the lift coefficient of the closed box girder is generally larger than that of the slotted box girder. The width of central slot has a significant effect on the VIV performance of the box girder, and the VIV amplitude of box girder decreases with an increase in slot width. When L/B changes from 0 to 0.20, the VIV amplitude varies by 40.9%. The change of the slot width will affect the movement of large vortices on the upper surface of a box girder and also affect the separation degree of incoming flow in the central region of the box girder, making VIV amplitude of streamlined box girder change.