大跨度斜拉索耦合振动机制及其STF阻尼器减振控制研究

As the span of cable-stayed bridge increasing, the influences of the coupled vibration between the deck and long-span cable on the dynamic performance of the whole bridge are getting more and more significant. The current mechanical models based on single component can hardly describe the characteristics of long-span cable accurately due to the coupled vibration from the deck. Moreover, the existing dampers which have some limitations of itself are difficult to effectively control the large amplitude vibration of the long-span cable. According to above problems, following work will be carried in this project. Firstly, the coupled mechanism of the parametric vibration and wind-induced vibration for long-span cable will be studied based on the cable-stayed beam coupled model; Secondly, establish the mechanical model of wind-rain-induced vibration of long-span cable with motion rivulet when subject to parametric excitation, after that, the mechanism of the wind-rain-induced vibration and its coupling with parametric vibration of long-span cable will be investigated; Finally, based on the shear thickening fluid (STF) smart material, and analysis the mechanical properties of the STF dampers. Furthermore, clarify the vibration control mechanism of the long-span cable based on the STF damper, reveal the effects of the coupling vibration between the deck and cable on the control performance of the STF damper, and evaluate the effective of the STF damper for the vibration control of long-span cable under strong wind or typhoon. The achievement of this project has significant theoretic and practical values in precise design and safety evaluation of long-span cable.

随着斜拉桥跨度的不断增加，全桥单位刚度减小，桥面与斜拉索的耦合振动对全桥动力性能的影响越来越显著。目前，单一构件的斜拉索力学模型难以准确描述斜拉索与桥面耦合振动特性，且现有阻尼器由于自身的局限性难以有效控制斜拉索的大幅振动。针对上述问题，本项目开展以下几方面研究：建立考虑参数激励的大跨度斜拉索风(雨)致振动的力学模型，研究参数振动和风(雨)致振动耦合作用下斜拉索的振动机理，量化相关参数对斜拉索振动和水线运动特征的影响；建立基于桥面、斜拉索和阻尼器耦合振动的力学模型，明确系统振动特性及其对阻尼器减振效果的影响机制；最后基于剪切增稠液(STF)材料，研究STF阻尼器力学性能，揭示基于STF阻尼器的大跨度斜拉索减振控制机理，给出耦合振动对STF阻尼器减振效果的影响并确定强/台风作用下STF阻尼器对大跨度斜拉索振动控制的效果。该研究对大跨度斜拉索精细化设计与安全评定具有重要的理论意义和应用价值。

本项目基于剪切增稠液体(STF)材料特性，在新型STF研发方面，研究了稀土氧化物对传统硅基STF力学性能的影响，分别利用SEM和XRD对STF分散相(SiO2)、分散介质(PEG)等的微观形貌和物相成分进行了观察，以确定引起STF宏观非线性力学性能变化的微观原因；配置出具有显著剪切增稠行为，且具有绝缘特征的STF，该STF有望用于实际工程振动控制中；配置出具有显著剪切稀化和剪切增稠效应的STF，基于该STF的夹层结构将具有时变刚度和阻尼特性；通过多壁碳纳米管制备出新型高性能增强型STF，并揭示了平板间距的增加不仅显著减小STF临界剪切速率，也显著提高了其峰值粘度，这为隔震领域中应用提供了重要设计依据。在STF阻尼器方面，阐明了足尺STF阻尼器的非线性滞回特性及其不同加载下的耗能机制，明确了STF阻尼器的力学特征；发现了STF阻尼力随着加载时间而减小的特性，并提出了预测该行为的计算公式，有助于STF阻尼器在工程振动控制中应用；进一步推导出STF阻尼器的理论计算模型并提出了STF阻尼器动力模型，且成功预测其滞回曲线，前者可为STF阻尼器在工程减振控制初步阶段提供计算依据，后者可为工程减震设计提供计算模型；