Developmental Study on Dynamically Stable Cable Systems

为了控制斜拉桥的风致振动，在斜拉桥斜拉索中采用了交叉索系。另一方面，对于悬索桥，为了简化主缆架设的猫道系统，研究了一种新的不使用风雨绳的缆索系统。因此，这项研究的主要目的是探索开发新的动态稳定的缆索系统的可能性。主要研究成果如下：1.采用模型试验和数值分析相结合的方法，对斜拉桥拉索系统的模态阻尼性进行了评价。2.提出了基于振型阻尼力能量表示的大跨度斜拉桥阻尼力分析方法，并应用于三种不同类型的大跨度斜拉桥：池口组合箱梁桥、横滨湾桁架桥和单面斜拉索体系的鹤立桥。计算了各大桥不同振型的振型阻尼比，并与实测值进行了比较。通过这些减振分析，显示了分析评价减振特性的巨大潜力。3.通过简化模型的一系列试验研究了猫道系统的动力特性。实验中不仅测量了拉索系统在线性响应中的模态阻尼，而且还测量了非线性行为对系统动力稳定性的影响。

A crossing rope system has been applied to stay cable in cable-stayd bridges in order to control their wind-induced vibrations. In case of suspension bridges, on the other hand, a new cable system without storm rope has been studied to simplify the catwalk system for main-cable erection. The main objective of this study is, therefore, to investigate the possibility of developing new cable system which is dynamically stable. The results obtained from the study are summarized as follows.1.The modal damping of cable system in cable-stayd bridges was evaluated by model experiment and numerical analysis. The damping effect of the crossing rope system is mainly clarified.2.The analytical method for the damping evaluation based on the energy representation of modal damping was proposed and applied to three different types of long-spanned cable-stayd bridges ; Ikuchi Bridge with composite box-girders, Yokohama Bay Bridge with truss girder and Tsurumi Tsubasa Bridge with the stay-cable system in single plane. The modal damping ratios for different modes of each bridge were evaluated and compared with the field-measured values. The high potential of the analytical evaluation of the damping characteristics was shown through these damping analyzes. The relation between modal damping of cable-stayd bridge and its cable system was also discussed.3.The dynamic characteristics of catwalk system was investigated by a series of experiments with simplified models. Not only the modal damping of the cable system in the linear response but also the effect of nonlinear behavior on the dynamic stability of the system were measured in the experiment.