大跨桥梁超长拉索振动和索-桥耦合振动问题研究

Affected by external excitation, vibration of long-span bridges and stay cables occurred easily, bring safety problems to bridges. With the increasing of span of bridges, geometric nonlinear effects due to the sag of super long cable has become increasingly evident, vibration of cables and coupled vibration of cables-bridge has become more and more prominent. Existing theoretical models can no longer meet the requirements of structural analysis. In this project, theoretical analysis models of wind-rain-induced vibration of continuous cable with moving rivulet, parametric vibration of cable, wind-rain and support excitation induced integrated vibration of cable which expressed in cable in-plane and out-of-plane modal coordinates based on catenary configuration, theoretical analysis models of coupled vibration of cables-bridge and coupled vibration of cables-bridge in wind-rain environment which expressed in cable in-plane and out-of-plane modal coordinates and continuous beam modal coordinates based on catenary configuration will be established. Using of non-linear vibration theory and numerical analysis methods, the vibration regularity and nonlinear vibration characteristics of super long cables and cables-bridge coupled vibration due to environment excitation will be studied systematically. At the same time, wind tunnel experiments using aeroelastic cable model, artificial rainfall wind tunnel experiments using rigidity segment cable with in-plain and out-of-plain vibration suspension system, parametric vibration experiments using single cable, cables-bridge coupled vibration experiments, and wind tunnel experiments using aeroelastic cable model subjected to support excitation will be carried out. Theoretical analysis results will be verified and theoretical analysis models will be corrected by experiments. From this project, explore the mechanism of vibration problems which described previously.

大跨桥梁及其拉索极易在外界的激励下发生振动，影响桥梁的安全运营。随着桥梁跨度的增长，由超长拉索的垂度产生的几何非线性效应随之增大，拉索振动和索-桥耦合振动问题变得日益突出，现有理论模型已不能满足结构分析的要求。本项目拟建立基于悬链线型、以拉索面内-面外各阶模态坐标表示的运动水线连续拉索风雨激振、拉索参数振动和拉索在风雨荷载与端部激励共同作用下的组合振动理论分析模型，以及以拉索面内-面外各阶模态坐标与连续梁各阶模态坐标表示的索-桥耦合振动和风雨环境下的索-桥耦合振动理论分析模型。运用非线性振动理论和数值分析方法，对环境激励下的超长拉索振动和索-桥耦合振动规律及其非线性特性进行研究。同时，拟开展气弹拉索风洞试验、面内-外振动的节段拉索人工降雨风洞试验、单索参数振动试验、索-桥耦合振动试验和端部激励下的气弹拉索风洞试验，检验和修正理论模型。通过本项目的研究，探寻上述振动问题的机理解释。

斜拉桥的主要受力构件斜拉索在风-雨环境以及桥面振动的激励下极易发生大幅振动，且会带来索-桥耦合振动问题，以及风雨激励和参数激励所引发的组合振动问题，危及桥梁的运营安全。. 本项目建立了基于悬链线型的，以拉索各阶模态坐标表示的拉索自由振动微分方程、连续弹性拉索风雨激振理论模型以及索-桥耦合振动微分方程，对拉索风雨激振特性、索-桥耦合振动特性以及风-雨环境中的索-桥耦合振动特性进行了研究；采用传递矩阵法和改进一阶随机平均法建立了一般线性粘弹性阻尼器耗能减振变频结构响应的非扩阶精确和近似解，并可进一步推广至连续体系。. 研究表明：拉索风雨激振以周期运动为主，在一定风速范围内会发生概周期运动；拉索参数和环境因素对拉索风雨激振亦有较大影响，以往实验研究和理论分析中，按照恒定风速确定拉索风雨激振振幅偏于不安全；当拉索长度较长时，基于抛物线和悬链线两种线型建立的拉索风雨激振理论模型的分析结果在拉索参振模态上出现差异，采用悬链线型建立的拉索风雨激振理论模型更为合理；风-雨环境对索-桥耦合振动有一定的抑制作用；基于传递矩阵法和改进一阶随机平均法建立的一般线性粘弹性阻尼器耗能减振变频结构响应的非扩阶精确和近似解，变量少，精度高，利于在工程减振设计中推广应用。. 本项目中建立的理论模型较以往的研究成果更能真实反映结构振动特性，且精度更高，研究成果可应用于桥梁的抗风、减振设计。