Central-slotted box girders are widely employed in long-span bridges owing to their advantageous flutter stability. However, the existence of a central slot can degrade their performance under vortex-induced vibrations (VIVs). To clarify the aerodynamic characteristics of a typical central-slotted box girder during VIVs, sectional model wind tunnel tests involving the synchronous measurement of pressure distributions and VIV responses were performed. The computational fluid dynamics (CFD) technique was also used to demonstrate the flow pattern development during VIV before qualitatively explaining the VIV mechanism of the central-slotted box girder. The surface pressure distributions at various amplitude-dependent VIV stages were measured and examined. The evolution of the aerodynamics was investigated from the perspective of the work done by the vortex-excited force (VEF). It was found that the aerodynamic effects on a central-slotted box girder during VIVs are featured with apparent nonlinear evolutionary characteristics. During the lock-in period, the wind-induced pressures at both upper and lower surfaces of the downstream box and the pressures at upper surface of the upstream box make greater contributions to the VEF, which are the main excitation sources of the torsional VIV. However, the contributions of the downstream and upstream boxes are opposite, showing positive and negative correlations with the VEF, respectively. It demonstrated that the positive contribution of the pressures at both upper and lower surfaces of the downstream box weakens the VIV performance of the central-slotted box girder as compared with a streamlined box girder. In addition, the central slot, which improves the correlating flow between the upper and lower regions around the downstream box, causes the distributed aerodynamic forces in these regions to enhance the VEF and perform positive work. This provides a reasonable explanation as to why the VIV effects of central-slotted box girders are typically stronger than those of streamlined box girders.

中央开槽箱梁由于其优越的颤振稳定性而被广泛应用于大跨度桥梁。然而，中心槽的存在会降低它们在涡激振动 (VIV) 下的性能。为了阐明典型中央开槽箱梁在 VIV 期间的空气动力学特性，进行了包括压力分布和 VIV 响应同步测量的截面模型风洞试验。在定性解释中央开槽箱梁的 VIV 机制之前，还使用计算流体动力学 (CFD) 技术来演示 VIV 期间的流型发展。测量和检查了各种振幅相关的 VIV 阶段的表面压力分布。从涡激力（VEF）所做的功的角度研究了空气动力学的演变。研究发现，VIV期间对中央开槽箱梁的气动效应具有明显的非线性演化特征。在锁定期，下游箱体上下表面风压和上游箱体上表面风压对VEF的贡献较大，是扭转VIV的主要激励源。然而，下游和上游框的贡献相反，分别与 VEF 呈正相关和负相关。结果表明，与流线型箱梁相比，下游箱体上下表面压力的积极贡献削弱了中央开槽箱梁的 VIV 性能。此外，中央槽改善了下游箱体周围上下区域之间的相关流动，使这些区域中分布的气动力增强了 VEF 并做正功。这为为什么中央开槽箱梁的 VIV 效应通常比流线型箱梁的 VIV 效应更强提供了合理的解释。导致这些区域中分布的空气动力增强 VEF 并执行正功。这为为什么中央开槽箱梁的 VIV 效应通常比流线型箱梁的 VIV 效应更强提供了合理的解释。导致这些区域中分布的空气动力增强 VEF 并执行正功。这为为什么中央开槽箱梁的 VIV 效应通常比流线型箱梁的 VIV 效应更强提供了合理的解释。