附加横向连接的双索结构振动特性的理论及试验研究

发布时间：2018-07-09 20:22

本文选题：拉索 + 辅助索　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：斜拉索作为斜拉桥的主要组成部分,其作用主要是将桥主梁和各种外部荷载传至桥塔上。由于斜拉索的质量比较小、而柔度比较大,因此很容易在风、雨、桥塔振动等外部激励作用下产生大幅振动,会引起拉索锚固端产生裂缝,破坏其表面的防腐材料,减少拉索的使用寿命,以及引起行车、行人的不安。工程中通常采用安装阻尼器、改变拉索表面形状的气动措施、安装辅助索等措施来抑制拉索的振动。气动措施减震机理非常复杂,并且针对外部的激励也比较单一,阻尼器则会受到斜拉索跨度增大的限制,而辅助索将各独立的拉索连接成索网结构,减少了拉索的有效长度,使各拉索的振动互相牵制耦合,显著提高索网系统的固有振动频率。但是辅助索减震的机理尚未清楚,优化方法尚未建立,辅助索减震有待进一步的研究。基于两个条件:(1)拉索振动幅度不大,辅助索一直处于张紧状态不会出现松弛情况(2)辅助索尺寸较小,忽略其振动对拉索振动的影响,则辅助索对拉索来说相当于一弹性的横向连接。本课题对接桥面辅助索-索网结构的微幅振动展开理论与试验研究,忽略辅助索振动对斜拉索振动的影响,鉴于索网结构的复杂性,本文建立了双拉索附加横向连接的简化索网结构和系统结构微分方程,对横向连接的刚度进行刚度无穷大和零的极限参数分析,以及横向连接的刚度在零到无穷大之间的非极限参数分析。主要研究了拉索长度比、横向连接的位置比、拉索频率比、拉索质量-张力比四个参数对前四阶系统面内自由振动频率的影响,以及参数之间的相互影响作用。针对理论分析结果,本文进行了双拉索系统结构模型试验。首先进行单索试验测试其面内外前二阶频率和阻尼比,其次在0.2L、0.4L位置安装形状记忆合金、尼龙线两种材料的横向连接,测试系统的面内外前二阶频率和阻尼比。发现附加横向连接的系统面内自由振动频率要明显高于单索的振动频率。对每一种工况进行面内自由振动理论计算,并与试验结果进行对比发现分析误差都小于5%,验证了理论分析模型及方程的准确性。对于该类拉索-横向连接系统的研究有一定的指导意义与实用价值。
[Abstract]:As the main component of the cable-stayed bridge, the cable-stayed cable is mainly used to transfer the main beam and various external loads to the tower. Because the mass of stay cable is small and flexibility is high, it is easy to produce large vibration under external excitation such as wind, rain and tower vibration, which will cause cracks at the anchor end of cable and destroy the anticorrosive material on its surface. Reduce the service life of lasso, and cause trouble for driving and pedestrians. In order to restrain the vibration of the cable, the damper is usually installed, the surface shape of the cable is changed and the auxiliary cable is installed. The damping mechanism of aerodynamic measures is very complicated, and the external excitation is relatively simple, and the damper will be limited by the increase of the span of the stay cable, and the auxiliary cable will connect each independent cable to the cable-netted structure, thus reducing the effective length of the cable. The vibration of each cable is pinched and coupled with each other, and the natural vibration frequency of the cable net system is improved significantly. However, the mechanism of auxiliary cable damping is not clear, the optimization method has not been established, and the auxiliary cable damping needs further study. Based on two conditions: (1) the vibration amplitude of the cable is not large, the auxiliary cable will not be relaxed in the state of tension all the time. (2) the size of the auxiliary cable is small, and the effect of the vibration on the vibration of the cable is ignored. The auxiliary cable is equivalent to an elastic transverse connection to the cable. In this paper, the theoretical and experimental research on the micro-amplitude vibration of the cable-cable net structure supported by the bridge deck is carried out, and the influence of the auxiliary cable vibration on the cable-stayed vibration is ignored. In view of the complexity of the cable-net structure, In this paper, the differential equations of simplified cable-net structures and system structures with additional transverse connections of double cables are established. The stiffness of transverse connections is analyzed by the limit parameters of infinite stiffness and zero stiffness. And the non-limit parametric analysis of the stiffness of the transverse connection between zero and infinity. The effects of four parameters, such as cable length ratio, position ratio of transverse connection, cable frequency ratio and cable mass-tension ratio, on the in-plane free vibration frequency of the first four order system are studied. Based on the results of theoretical analysis, the structural model test of double cable system is carried out in this paper. First, the second order frequency and damping ratio in front and out of plane were tested by single cable test. Secondly, the shape memory alloy and the transverse connection of nylon wire were installed at 0.2L 0.4L, and the pre-plane second-order frequency and damping ratio of the system were measured. It is found that the in-plane free vibration frequency of the system with transverse connection is obviously higher than that of single cable. The theoretical calculation of in-plane free vibration is carried out for each working condition, and the analysis error is less than 5 by comparing with the experimental results, which verifies the accuracy of the theoretical analysis model and equation. It has certain guiding significance and practical value for the research of this kind of cable-transverse connection system.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441.3;U448.27

【引证文献】