基于模态安装位置比的斜拉索-阻尼器参数研究

Study of Stay Cable and Damper Parameters Based on Modal Installation Position Ratios

为扩展常规斜拉索阻尼器优化理论的适用范围,针对高阶振型和阻尼器安装位置较高的情况,将安装位置比和斜拉索振型模态相结合,提出模态安装位置比的定义,代替常规的安装位置比,评估斜拉索安装阻尼器后的阻尼特性。并以某长江大桥为例,对其最长斜拉索的阻尼参数采用该方法进行分析。结果表明:随着振型阶次的增加,斜拉索的模态安装位置比呈先增大后减小的趋势,阻尼器安装位置为振型峰值时达到最大值0.5;随着振型阶次的增加,各阶模态对应的最大阻尼对数衰减率开始保持不变,当阻尼器安装位置超过振型峰值后,逐渐减小;基于模态安装位置比的阻尼器参数分析方法可以准确评估斜拉索安装阻尼器后的阻尼特性。

T o ex p an d th e ap p lic a t io n ran g e of th e o p timizat io n th e o r ie s fo r th e co n v en tio n al stay cables and dampers, the definit ion of the modal instal lat ion posi t ion rat io is proposed in the l ight of the high-order vibrat ion modes of the stay cables and the high instal lat ion posi t ions of the dampers and also in combined consideration of the instal lat ion posi t ion rat ios and the vibrat ion modes. The modal instal lat ion posi t ion rat io proposed herewi th is intended to replace the conven-t ional instal lat ion posi t ion rat io and to assess the damping characterist ics of the stay cables in-stal led wi th the dampers. A Changjiang River Bridge is selected as a case study and the damping parameters of the longest stay cable of the br idge are analyzed, using the method of the modal in-stal lat ion posi t ion rat io. The results show that wi th the increase of the orders of the vibrat ion modes, the modal instal lat ion posi t ion rat ios of the stay cables exhibi t the tendencies of increasing fi rst and decreasing then. At the peak values of the vibrat ion modes, the instal lat ion posi t ions of the dampers reach the maximum values of 0. 5. Wi th the increase of the orders of the vibrat ion modes, the maximum damping logari thm decrement rat ios corresponding to the different orders of the vibrat ion modes start to stay unchanged. When the instal lat ion posi t ions of the dampers exceed the peak values of the vibrat ion modes, the damping logari thm decrement rat ios gradual ly de-crease. The analysis method of the damper parameters based on the proposed modal instal lat ionposi t ion rat io can be used to accurately assess the damping characterist ics of the stay cables in-stal led wi th the dampers.