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Vortex-induced Vibration and Control of Split Three-Box Girder Bridges
Structural Engineering International ( IF 1.1 ) Pub Date : 2021-06-24 , DOI: 10.1080/10168664.2021.1932700
Fengfan Yang 1 , Shixiong Zheng 1 , Zhengxi Yan 1
Affiliation  

Abstract

The vortex-induced vibration (VIV) performance and aerodynamic mechanism of VIV control of a split three-box girder bridge were investigated numerically by Computational Fluid Dynamics (CFD). Large-scale section model wind tunnel tests show that the integrated countermeasure combined by 30% ventilation ratio grids and new scheme for maintenance tracks can effectively restrain vertical and torsional VIVs. The reliability of numerical method is verified by comparing static three-component coefficients and Strouhal numbers obtained from CFD and wind tunnel tests. The flow structure and changes of aerodynamic forces were analyzed via delayed detached-eddy simulation (DDES). For the original section, large-scale vortices form with shedding behind the safety barrier of the upstream box and behind the maintenance tracks, as well above the downstream highway box, introducing periodic pulsating lifts and moments that result in severe VIVs. The grids can effectively reduce the size of vortices in the gaps, prevent the flow from fluctuating and reduce the pressure difference between upper and lower surfaces. The torsional VIVs at non-negative attack angles are not controlled because the grids cannot interfere with the vortices behind the maintenance tracks. The new scheme for maintenance tracks, which has grid-like effects, can eliminate the torsional VIVs at non-negative attack angles by preventing the vortices behind maintenance tracks from impacting downstream boxes. The aerodynamic force components are analyzed to find that box 1 mainly contributes the mean values and box 3 mainly contributes the fluctuating values. The integrated countermeasure can reduce the mean and RMS values of aerodynamic forces to varying degrees. The streamlines and RMS pressure contours indicate that the integrated countermeasure effectively reduced the wake height and vortices motion range, which is conducive to VIV control. This work lays a solid foundation for an in-depth understanding of the aerodynamic characteristics and optimization mechanism of split three-box girder bridges.



中文翻译:

分体式三箱梁桥涡激振动与控制

摘要

采用计算流体动力学 (CFD) 方法对分体式三箱梁桥的涡激振动 (VIV) 性能和 VIV 控制的气动机制进行了数值研究。大型断面模型风洞试验表明,30%通风比网格与维修轨道新方案相结合的综合对策能够有效抑制垂直和扭转振动。通过对比CFD和风洞试验得到的静态三分量系数和Strouhal数,验证了数值方法的可靠性。通过延迟分离涡模拟(DDES)分析了流动结构和气动力的变化。原断面上游箱体安全屏障后、检修轨道后形成大范围涡流脱落,以及下游高速公路箱上方,引入周期性脉动升力和力矩,导致严重的 VIV。格栅可以有效减小缝隙中涡流的大小,防止流动波动,减小上下表面的压力差。非负攻角的扭转 VIV 不受控制,因为网格不能干扰维护轨道后面的涡流。维修轨道的新方案具有类似网格的效果,可以通过防止维修轨道后面的涡流影响下游箱子来消除非负攻角的扭转 VIV。分析气动力分量发现,方框1主要贡献均值,方框3主要贡献波动值。综合对策可以不同程度地降低气动力的平均值和均方根值。流线和均方根压力等值线表明,综合对策有效降低了尾流高度和涡运动范围,有利于VIV控制。该工作为深入理解分体式三箱梁桥的气动特性及优化机理奠定了坚实的基础。

更新日期:2021-06-24
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