Study on Damping of Structural Cables and Development of High-Damping Cable

1.通过悬索模型的自由振动试验和有限元分析，研究了悬索弯曲振动的模态阻尼。（1）拉索模态阻尼的主要原因是由滞回耗能引起的内阻尼和由支座耗能引起的支座阻尼。(2)拉索的内阻尼与自由振动附加动应变的平方成正比。因此，在模态过渡区，面内对称模态的模态阻尼比其他模态的阻尼大。(3)初始张力较低时，拉索的内阻尼较大，但当初始张力超过抗拉强度的20%时，拉索的内阻尼几乎与初始张力无关。(4)在模态过渡区，支承柔度对对称模态的模态阻尼有显著影响。(5)支座阻尼对悬索模态阻尼的贡献与支座振幅的平方近似成正比。采用以下思路对高阻尼拉索进行了可行性研究：拉索的非均匀化可能导致动应变增加，从而增加滞回耗能;通过在拉索中插入粘弹性材料来增加剪切阻尼;以及通过使用液体或铅粒的小球形阻尼器来增加外部阻尼。

1. The modal damping of flexural oscillation in suspended cable was investigated through free oscillation experiments with cable model and through finite element analyses. The brief conclusions obtained are as follows: (1) Primary causes of modal damping of cable are the internal damping caused by the hysteretic energy loss and the support damping due to the energy loss at support. (2) The internal damping of cable is in proportion to the square of additional dynamic strain of free oscillation. The modal damping of in-plane symmetric mode is, therefore, larger than other modal damping in the modal transition region. (3) The internal damping of cable is larger for lower initial tension but almost independent on the initial tension when the initial tension exceeds about 20 percent of the tensile strength. (4) The flexibility of support has significant effect upon the modal damping of symmetric mode in the region of modal transition. (5) Contribution of support damping to modal damping of suspended cable is approximately proportional to the square of modal support-amplitude.2. The feasibility study on high-damping cable was conducted with the following ideas; the increase of hysteretic energy loss due to the increase of dynamic strain which may be caused by making the cable non-uniform; the addition of shear damping by inserting viscoelastic materials into cable; and the addition of external damping by using small spherical damper with liquid or lead grains.