【摘要】 以经典弦振动理论为基础,建立斜拉索振动分析的有限元模型,提出考虑抗弯刚度的斜拉索平衡索曲线迭代计算方法。讨论抗弯刚度对斜拉索平衡索曲线的影响,绘制出距垂比随拉弯刚度比的变化曲线,得出了斜拉索的垂度随抗弯刚度的增大而减小的变化规律。针对西昌斜拉桥25对斜拉索的模态进行精确分析,以有限元的方法验证了斜拉索的模态超越现象,分别绘制频率和振型随索力的变化曲线,归纳索频率变化规律,提出索力测量的实用计算方法,采用频差法来判断实测各阶频率的阶数,并且以第2阶频率来进行索力计算。经工程实例验证,考虑抗弯刚度的斜拉索平衡索曲线迭代计算方法可以有效排除由模态超越带来的索力计算偏差,适用于各种长度的斜拉索以及在施工过程中各阶段的索力测量计算。更多还原

【Abstract】 Based on classical string vibration theory,the finite element model for vibration analysis of stay cable was created,and a method of iteratively computing stay cable balance curve considering flexural rigidity was proposed.The influence of flexural rigidity on stay cable balance curve was discussed,the curves of distance-sagging ratio varying with tension/bending stiffness ratio was plotted,and the regularity of the bigger the flexural rigidity,the smaller the sagging of stay cables was presented.The modes of 25 pairs of cable of Xichang cable stayed bridge were accurately analyzed,the mode crossover of stay cables was testified by finite element method,the curves of frequency and mode shape varying with cable force were separately plotted,the changing rule of cable frequency was induced,the practical cable force computing method was proposed,frequency-difference method was adopted to judge the order of actual measured frequencies,and the second order frequency was used to compute cable force.The engineering instance analysis testified that the method of iteratively computing stay cable balance curve considering flexural rigidity could rule out errors caused by mode crossover,and could be applied to stay cables with any lengths and forces in any construction periods.更多还原