国产粘性阻尼器的实索减振试验研究

在拉索上附加耗能减振阻尼器是斜拉索振动控制的主要手段之一,而拉索在附加非线性粘性阻尼器后的阻尼特性尚未见试验研究报道。本文对一种国产非线性粘性阻尼器进行了实索减振试验。在工厂内张拉一根长215.58 m的拉索,利用人工激振拉索至一定振幅后测得的振动衰减的位移时程曲线,计算了空索及拉索—阻尼器系统前三阶模态的对数衰减率值;同时也测量了阻尼器工作时的阻尼力。试验结果表明,空索的内阻尼值很小,可忽略不计;而拉索—阻尼器系统的对数衰减率值则与振幅相关。试验测得拉索—阻尼器系统的前三阶模态的对数衰减率均值达到了0.04,可以有效地抑制拉索的振动。将实测对数衰减率平均值与理论计算对数衰减率最大值比较,得到拉索减振设计时可采用的阻尼器效率系数。

Full-scale Cable Vibration Mitigation Experiment Using Viscous Damper

Dampers have been used for vibration mitigation of stay cables;however,there are few literatures on the test of full-scale stay cable attached with nonlinear viscous damper.In this paper,a full-scale cable vibration mitigation experiment was conducted by using a 215.58 meters long stay cable and a set of home made nonlinear viscous dampers.The cable was excited by human power and then the free decay curve of cable and cable-damper system was measured.The damper force was also measured during the test.Then the logarithmic decrement of cable could be calculated from the displacement free decay curve.It was found that the internal damping of free cable is very small;the derived logarithmic decrement of cable-damper system varied with amplitude.The mean value of logarithmic decrement of cable-damper system was about 0.04,large enough for mitigation of possible cable vibration.Comparison of the mean value of measured logarithmic decrement with theoretical maximum was conducted.It was found that the measured maximum logarithmic decrement value was smaller than the theoretical maximum due to the effect of stiffness of supporter and damper.The efficiency ratio,which is the mean value of logarithmic decrement divided by theoretical maximum,was derived for possible practical damper design.