The vortex-induced vibration performance of railway rectangular box girders

Rectangular steel box girders offer advantages such as a simple frame, high stability, and strong bearing capacity. Despite their widespread use, these girders are susceptible to vortex-induced vibration (VIV), posing challenges to the wind-resistant design. This study aims to comprehensively understand the VIV characteristics of different rectangular steel box girders, based on which effective VIV suppression measures are proposed. First, the rectangular box girders with aspect ratios of 4:1, 6.7:1, and 9:1 are selected to investigate the VIV performance through sectional model wind tunnel tests. The test results reveal significant differences in VIV characteristics among the test sections. The section with the most pronounced vertical VIV is the model with an aspect ratio of 4:1. In contrast, the section with the most significant torsional VIV is the one with an aspect ratio of 9:1. The box section with an aspect ratio of 6.7:1 also exhibits noticeable vertical and torsional VIV responses. Subsequently, the wind tunnel test result regarding the suppression of VIV indicates that setting symmetrical wind fairings with 1/8 times the section width has varying effects for each aspect ratio section. Symmetrical wind fairings reduce the VIV amplitude of the box girder with aspect ratios of 4:1 and 9:1 under different wind attack angles but increase the VIV response of the box girder with an aspect ratio of 6.7:1 at 0°, +3°, and +5° wind attack angles. Finally, the computational fluid dynamics numerical calculations simulate the flow field of each testing section, determining the vortex shedding mode of the rectangular box section for each aspect ratio, both before and after setting the wind fairings. The research results can provide a reference for the aerodynamic design and aerodynamic measures to suppress VIV in long-span bridges.