框架结构损伤定位的比例柔度矩阵分解法试验研究

Experimental validation of a proportional flexibility matrix decompositionbased damage localization method for frame structures

提出了基于比例柔度矩阵LU分解的结构损伤定位方法。该方法从结构振动响应入手,首先识别出结构前几阶模态振型和频率,构建结构比例柔度矩阵;然后对损伤前后的比例柔度矩阵差进行LU分解;最后基于U矩阵和曲率方法构建损伤指标对损伤进行定位。基于某20层框架结构进行了数值模拟损伤定位研究;并在实验室设计、建造一个6层集中质量剪切型框架模型,基于该模型分别进行了振动台试验和脉冲激励试验。模拟和试验下的单损伤和多损伤工况结果均表明:提出的方法能准确地对结构损伤进行定位。该方法只需要损伤前后测点的振动响应数据,不需要结构有限元模型,避免了复杂的结构有限元模型建模和模型修正工作;并且构建一个满足精确度的比例柔度矩阵只需要结构的前几阶低阶模态参数,而低阶参数的识别准确性相对较高,这些优点均为该方法的工程应用奠定了基础。

The present work has proposed a damage localization method based upon LU decomposition of proportional flexibility matrix.Firstly,several low-frequency modal frequencies and mode shapes are identified based on the vibration responses;then proportional flexibility matrices before and after damage are extracted respectively.Secondly,LU decomposition of the change of proportional flexibility matrix is implemented.Finally,the damage index is extracted based on the U matrix and curvature method to locate the damage.Simulations have been implemented based on a 20-storey shear building model;moreover,a 6-storey lumped-mass frame model has been built in the laboratory,then its shaking table tests and pulse tests have been implemented also.Both numerical and experimental results of single and multiple damage cases indicate that the proposed method can locate the damage very well.With responses before and after damage,the method does not require a structural finite element model;thus,establishing a numerical model and model updating can be avoided.Besides,the flexibility matrix can be estimated with sufficient accuracy by only using several low-frequency modes which can be identified well.All of these lay agood foundation for engineering application of the proposed method.