| 大跨度悬索桥的多阶模态竖向涡振与控制 |
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| 引用本文： | 华旭刚,黄智文,陈政清.大跨度悬索桥的多阶模态竖向涡振与控制[J].中国公路学报,2019,32(10):115-124. |
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| 作者姓名： | 华旭刚 黄智文 陈政清 |
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| 作者单位： | 湖南大学 风工程试验研究中心, 湖南 长沙 410082 |
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| 基金项目： | 国家自然科学基金项目（51422806） |
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| 摘 要： | 大跨度悬索桥具有多个竖向模态密集分布的特性。在常遇风速范围内，从低到高的各阶竖向模态随风速升高而逐个发生涡振，这就是大跨度悬索桥的多阶模态涡振问题。针对这一问题开展深入研究，讨论中国公路桥梁抗风设计规范中竖向涡振容许振幅的合理性；阐述了利用节段模型风洞试验和理论分析综合预测实桥多阶模态竖向涡振响应的基本方法，得到了各模态阻尼比相等时悬索桥各阶模态竖向涡振振幅基本相等的结论，并通过特殊设计的悬索桥竖向等效气弹模型和塔科马桥涡振实测资料，验证了这一结论；指出在既有桥梁上追加气动措施或安装调谐质量减振器抑制悬索桥多阶模态涡振都有很大的难度，进而提出了在加劲梁与桥塔之间安装直接耗能阻尼器的设想，并进行了气弹模型试验验证；讨论了采用电涡流阻尼器进行半主动涡振控制的可行性。研究结果表明：在相同阻尼比条件下大跨度悬索桥各阶竖弯模态的最大涡振振幅基本相等；依据最大加速度幅值按频率比的平方增加的原理，满足人体振动舒适性的高阶竖弯模态的容许振幅必然小于低阶模态，因此要更加重视起振风速在容许行车风速（25 m·s-1）以内的高阶竖弯模态涡振；对于漂浮体系悬索桥，在加劲梁与对应桥塔之间设置阻尼器可有效抑制多阶模态涡振。
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| 关 键 词： | 桥梁工程 悬索桥 风洞试验 涡振 振动控制 阻尼器 |
| 收稿时间： | 2018-11-13 |
Multi-mode Vertical Vortex-induced Vibration of Suspension Bridges and Control Strategy |
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| HUA Xu-gang,HUANG Zhi-wen,CHEN Zheng-qing.Multi-mode Vertical Vortex-induced Vibration of Suspension Bridges and Control Strategy[J].China Journal of Highway and Transport,2019,32(10):115-124. |
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| Authors: | HUA Xu-gang HUANG Zhi-wen CHEN Zheng-qing |
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| Affiliation: | Wind Engineering Research Center, Hunan University, Changsha 410082, Hunan, China |
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| Abstract: | Long-span suspension bridges contain numerous closely spaced vertical modes, and these modes, in order of natural frequency, may develop vortex-induced vibrations (VIV) in turn with increase of wind velocity.This multi-mode vertical VIV problem has become a challenge in the development of suspension bridges. In this study, the problem has been addressed from several aspects. First, the rationality of the allowable amplitude of vertical VIV for different vibrational modes is discussed in reference to the wind-resistant design specifications for highway bridges in China. Second, the analytical method for predicting multi-mode vertical VIV is formulated on the basis of section model tests and theoretical analysis. The results indicate that when the same damping ratio is used, the maximum VIV amplitudes are almost the same for different vertical modes of suspension bridges. This is further verified by wind tunnel tests using a specially-designed novel aeroelastic model of suspension bridges and by existing measurement data of the Old Tacoma Narrows Bridge. Third, because it is quite difficult to apply aerodynamic countermeasures or tuned mass dampers on existing bridges experiencing VIV, a new vibration control strategy is proposed to suppress multi-mode VIV by using the direct energy dissipation devices installed between the tower and girders. The efficacy of the control strategy is preliminarily evaluated by conducting experiment susing the novel aeroelastic model, and the feasibility of semi-active control of multi-mode VIV by employing an eddy current damper is discussed. Through above study, it is concluded that the maximum amplitudes of VIV for different vertical modes were almost the same if their damping ratios were also the same; thus, their acceleration amplitudes increase in proportion to the square of natural frequency. In order to achieve the same allowable maximum acceleration amplitudes, the allowable VIV amplitudes for higher modes must be smaller than those for lower modes, which implies that VIV at higher modes should be considered with priority in wind-resistant designs of suspension bridges. Further, the direct energy dissipation device installed between the pylon and floating girder is shown to effectively suppress multi-mode VIV in multi-span suspension bridges without immediate support. |
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| Keywords: | bridge engineering suspension bridge wind tunnel test vortex-induced vibration vibration control damper |
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