斜拉桥地震响应分析中阻尼矩阵精确估计研究

INVESTIGATION OF DAMPING MATRICES ACCURATE ESTIMATION OF CABLE-STAYED BRIDGES BASED ON NON-PROPORTIONAL DAMPING

斜拉桥阻尼组成复杂,阻尼矩阵的精确确定比较困难,在假定斜拉桥子结构(梁、塔、索、支座等)的阻尼系数不随频率和振幅变化的情况下,利用状态空间方法计算了斜拉桥有阻尼频率和模态,提出一种根据已知少数振型阻尼比通过反复迭代求得阻尼系数及阻尼矩阵估计值的方法。利用斜拉桥非正交阻尼计算理论,结合参数敏感性分析和最小二乘法优化算法,可以精确计算斜拉桥各子结构的阻尼系数,得到斜拉桥阻尼矩阵的精确估计,为建立斜拉桥精确的有限元模型提供基础。

The damping makeup of cable-stayed bridges is complicated.It is a tough work to determine the damping matrices accurately.On the assumption of the damping coefficients of substructures in cable-stayed bridge（such as girder,tower,cable and support etc） are constant value and don＇t vary with frequency or vibration amplitude.An iteration method of damping coefficients and damping matrices estimation was presented.It was based on several known modal damping ratios,through the calculation of complex damped frequency and modal shape utilizing the state-space methodology.With the theory of non-proportional damping calculation of cable-stayed bridge,incorporating parameter sensitivity analysis and the least square optimization procedure,the damping coefficients of substructures were accurately determined,and the damping matrices were estimated with relatively high accuracy.Which provided a basis for setting up accurate finite element model of cable-stayed bridges.