斜拉索辅助索减振的性能分析与试验研究

Analysis and experiments on vibration mitigation of stay cables using cross ties

为了提高斜拉索辅助索的减振性能,分别采用辅助索阻尼器,辅助索索端阻尼器及主索索端阻尼器进行有限元及理论分析并用试验检验.有限元模型为一主跨1.4km斜拉桥的1/4索面,由38根斜拉索和4根辅助索组成.用ANSYS进行时程分析,忽略拉索内在阻尼,用MATLAB对数据进行处理.结果表明:阻尼器变形越大越能获得较大的最优模态对数衰减率;3种阻尼器均可使索网前3阶对数衰减率达到0.04,且安全系数达到2以上;主索索端阻尼器与辅助索索端阻尼器分别为最优阻尼共同作用时,减振效果不为二者单独作用之和,且低于辅助索索端阻尼器单独作用时的减振能力;辅助索索端阻尼器或主索索端阻尼器与辅助索阻尼器分别为最优阻尼共同作用时,减振效果约为二者单独作用之和.试验模型有3根主索和1根辅助索组成.试验结果证实有限元分析结果正确,二者的对数衰减率随阻尼器阻尼变化趋势相同.

In order to improve the vibration mitigation performance of cross ties,a cross-tie damper,a cable-end damper and a cross-tie-end damper are used separately to do theoretical analysis and FEM(finite element method) simulation,and the results are verified by experiments.The finite element model is consisted of 38 stay cables and 4 cross ties,and is 1/4 cable plane of a cable-stayed bridge whose main span is 1.4 km.ANSYS is used in the finite element analysis to do the time-history analysis,and the intrinsic damp of the cables are ignored.Then,MATLAB is used to tackle the data.The FEM results show that the larger deformation of the damper can induce the greater decay rate.Using the three dampers,the first 3 mode logarithmic decay rate of the cable net can achieve 0.04 and the safety factor is more than 2.When the cable-end damper and the cross-tie-end damper have optimal damping,the damping effect of the combination of them is not the superposition of them and is lower than that of the cross-tie-end damper.When the cable-end damper or the cross-tie-end damper works with the cross-tie damper and they have optimal damping,the damping effect of the combination of them is the superposition of them.The experimental model is consisted of three stay cables and one cross tie.The experimental results show that the FEM results are correct.Both the results have the same trend of the decay rate with the increase of the damp.