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Aerodynamic performance of Π-shaped composite deck cable-stayed bridges including VIV mitigation measures
Journal of Wind Engineering and Industrial Aerodynamics ( IF 4.8 ) Pub Date : 2020-11-25 , DOI: 10.1016/j.jweia.2020.104451
Hua Bai , Rui Li , Guoji Xu , Ahsan Kareem

This study systematically investigates the influence of the cross-sectional aspect ratio (B/H) and four different aerodynamic mitigation measures, i.e., the fairing, lower central stability plate, inverted L-shaped edge plate, and lower horizontal edge plate, on the performance of cable-stayed bridges, with π-typed composite deck, i.e., π section, due to vortex-induced vibrations (VIV). The study utilized wind tunnel tests and limited CFD simulations by varying bridge dimensions. First, based on a survey of existing cable-stayed bridges with the π-typed composite deck, three-section models with different aspect ratios were studied and their corresponding vibration characteristics for the vertical and torsional VIVs were analyzed. Then, the vibration suppression effects of mitigation measures with several variants in shape were investigated to determine an effective mitigation measure, i.e., with favorable aerodynamic stability, for the π section deck. The vibration suppression mechanism for three selected cases was further assessed using numerical simulation. The results show that: (a) for the π section model with the aspect ratio in the range of 9.05–11.96, increasing the ratio value will delay the onset wind speed of the vertical and torsional VIVs; (b) In the case of a low ratio of the torsional frequency to vertical bending frequency, there are often special phenomena where the vertical and torsional vibrations coexist. However, a larger aspect ratio would result in more independent vertical and torsional vibrations; (c) Regarding the vibration suppression effect, based on the limited studied cases, a small fairing can be superior to large fairings; (d) Different forms of the lower central stability plate have a good suppression effect on the vertical VIV; (e) The use of inverted L-shaped edge plate with a ​= ​23H and b ​= ​12H is identified to result in the best vibration suppression for both the vertical and torsional vibrations among the considered mitigation measures, where a and b are the size parameters of the inverted L-shaped edge plate; and (f) The lower horizontal edge plate cannot effectively improve the torsional VIV performance. This study offers guidance on the performance of composite cable-stayed bridge with the π section in isolation and equipped with mitigation measures to aid in the engineering design practice.



中文翻译:

包括VIV缓解措施的shaped形复合甲板斜拉桥的空气动力学性能

本研究系统地研究了横截面纵横比(B / H)和四种不同的空气动力学缓解措施,即整流罩,下部中央稳定板,倒L形边缘板和下部水平边缘板,用于斜拉桥的π型复合桥面,即π由于涡流引起的振动(VIV)。该研究利用风洞测试和通过改变桥梁尺寸进行有限的CFD模拟。首先,在对现有的具有π型复合桥面的斜拉桥进行调查的基础上,研究了不同纵横比的三截面模型,并分析了它们对应于垂直和扭转VIV的振动特性。然后,研究了几种形状变化的缓解措施的减振效果,以确定一种有效的缓解措施,即具有良好的空气动力学稳定性,用于π截面甲板。使用数值模拟进一步评估了三种选定情况的振动抑制机制。结果表明:(a)对于长宽比在9.05–11.96范围内的π截面模型,增大比例值将延迟垂直和扭转VIV的起始风速;(b)在扭转频率与垂直弯曲频率之比较低的情况下,通常会存在垂直振动和扭转振动共存的特殊现象。但是,较大的宽高比将导致更独立的垂直和扭转振动。(c)关于减振效果,根据有限的研究情况,小型整流罩可以优于大型整流罩;(d)不同形式的下部中央稳定板对垂直VIV有良好的抑制作用;一个 =23Hb  =1个2在考虑的缓解措施中,H被确定为对垂直和扭转振动都具有最佳的振动抑制效果,其中ab是倒L形边缘板的尺寸参数;(f)下部水平边缘板不能有效地改善VIV扭转性能。这项研究为π截面隔离的复合斜拉桥的性能提供了指导,并配备了缓解措施以帮助工程设计实践。

更新日期:2020-11-25
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