Study on Development of High Damping Structural Cables

由于在大型结构中作为受拉构件的结构索通常非常柔韧性，重量相对较轻，耗能较小，因此各种类型的振动问题在索结构中经常得到证明。为了抑制不同类型缆索的振动，已经采用了多种控制措施，但大多数都只是在缆索上增加阻尼装置。本研究的主要目标是开发高阻尼电缆，其本身具有更高的能量耗散性，并且对任何类型的电缆振动都更有效。从研究中得到的结果总结如下：考虑两种方法，对增大索内阻尼的可能性进行了分析和实验研究。一种是增加与模态振动相关的索的动应变的结构措施，另一种是增加本身滞回能量损失的材料措施。在缆索股与外护套之间插入粘弹性材料被认为是一种物质措施。从理论上估计了经阻尼处理后电缆的等效损耗因子，并得到了阻尼增大的条件。通过粘弹性厚板包裹钢条索模型的一系列实验，研究了阻尼处理增大阻尼的可能性。通过这些分析和实验研究，我们发现要大幅度扩大电缆的滞回线是不容易的。对二次电缆被动控制和主动波控制进行了研究，并对其控制性能进行了实验和分析验证。

Various types of vibration problems have been frequently evidenced in cable structures because the structural cable used as tension member in large scale structures is generally very flexible, comparatively light and less energy-dissipative. Many kinds of control measures have been applied for suppressing different types of cable vibrations, but most of them are just adding damping devices to the cables. The main objective of this study is to develop high damping cable which itself is more energy-dissipative and more generally effective for any type of cable vibrations. The results obtained from the study are summarized as follows.1.The possibility of increasing the internal damping of cable was investigated analytically as well as experimentally by considering two methods. One is a structural measure which can increase the dynamic strain of cable associated with the modal vibration and another is a material measure which increases the hysteretic energy loss itself.2.Inserting visco-elastic material between cable strands and outer cover was considered as a material measure. The equivalent loss factor of the cable with the damping treatment was theoretically estimated and the conditions for damping enlargement were obtained.3.The possibility of damping enlargement by the damping treatment was studied also by a series of experiments with the cable models which are steel rods wrapped by visco-elastic thick plates. As a result of these analytical and experimental studies, we found that it is not easy to significantly enlarge the hysteresis loop of cable.4.The passive control by secondary cables and the active wave control were also studied and their control performances were checked experimentally and analytically.