Investigation of Vortex-Induced Vibration Behavior of a Single-Sloped Box Girder

Wind-induced vortex-induced vibrations pose serious threats to the structural safety and service performance of long-span bridges. Wind tunnel tests on a coastal bridge reveal that the direction of the incoming flow can lead to significantly different vortex-induced vibrations in asymmetric sections. This paper systematically investigates the vortex-induced vibration characteristics under bilateral incoming flows using computational fluid dynamics. The results indicate that the incoming flow direction considerably influences the vortex shedding pattern and vibrational response: when the flow comes from the high web side, large-scale periodic vortex shedding occurs, with the frequency locking onto the fundamental structural frequency, resulting in strong vibrations; when the flow comes from the low web side, the vortex structures break down, the shedding frequency desynchronizes, and the response is significantly reduced. Furthermore, a quantitative analysis of the influence of the transverse slope parameter (0–2.25%) on the vortex-induced vibration response of a single-slope cross-section is conducted. It is found that an increase in slope amplifies the effective angle of attack on the top plate and enhances the vortical energy, leading to a 58% increase in vertical displacement. The research findings provide a theoretical basis and parametric design support for the precise wind-resistant design of single-slope steel box girders.