斜拉桥拉索减振阻尼器对拉索索力测量的影响研究

Study of Cable Tension Measurement for Stay Cable Attached Damper

针对采用频率法测量拉索索力时拉索外加阻尼器对索力测量精度影响的问题,提出了考虑拉索垂度的拉索-阻尼器系统模态频率的分析方法,研究了阻尼器安装的相对高度、拉索的计算长度、阻尼系数等对拉索模态频率的影响程度和规律,获得了消除拉索减振阻尼器对索力测量精度影响的办法。研究表明,外加阻尼器对拉索低阶模态频率影响很大,采用高阶模态频率测量拉索索力时,索力测量能获得很好的精度。随着拉索-阻尼器系统相对安装长度和阻尼系数的增大,阻尼器对拉索模态频率的影响也越大,当阻尼系数增加到一定程度后,拉索的高阶模态频率基本与阻尼系数无穷大时的频率接近,阻尼器相当于固定支撑。以岳阳洞庭湖大桥A11号拉索为例,验证了该方法合理可行。

For tension precise measurement of stay cable with external dampers by using vibration frequency method, the analyzing method of modal frequency of cable-damper system which considers cable sag was proposed. The influence extent and roles of the modal frequency of cable versus the relative height of damper installment, effective length of cable and damper coefficient were analysed, and the method to overcome the influence of cable damper upon measuring accuracy of cable tension was proposed. The research results show that low modal frequencies of cable are changed obviously due to external dampers and the measurement precision of tension can be obtained with high modal frequencies. The results also show that the influence of damper on modal frequency increases with the increases of relative height of damper installment and damper coefficient, and the high modal frequencies of cable close to the frequencies when damper coefficient increases to infinity and location of damper is equivalent to fixed support. The proposed method was verified with stay Cable No. A11 of Dongting Lake Bridge of Yueyang. It indicates that the method is reasonable and feasible.