Developmental Study on Dynamically Stable Cable Systems

为了控制斜拉桥的风致振动，在斜拉桥的拉索上采用了交叉索系。另一方面，在悬索桥的情况下，研究了一种新的没有风暴绳的缆索系统，以简化主缆索架设的猫道系统。本研究的主要目的是，因此，调查开发新的电缆系统，这是动态稳定的可能性。主要研究成果如下：1.通过模型试验和数值分析，对斜拉桥拉索系统的模态阻尼进行了评估。提出了基于模态阻尼能量表示的阻尼分析方法，并将其应用于三种不同类型的大跨度斜拉桥：组合箱梁的生池大桥、桁架梁的横滨海湾大桥和单平面斜拉索的鹤见翼大桥。对每座桥梁的不同模态的模态阻尼比进行了评估，并与现场实测值进行了比较。通过这些阻尼分析，显示了阻尼特性分析评估的高潜力。通过简化模型试验研究了猫道系统的动力特性。实验中不仅测量了索系统在线性响应时的模态阻尼，而且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.