基于加速度二次协方差矩阵参数变化比法的环境振动下结构损伤识别

在白噪声环境激励下，结构加速度响应的自相关/互相关函数构成一个新的二次协方差（CoC）矩阵，组成这一协方差矩阵的元素经证明是结构模态参数（频率、振型、阻尼）的函数；与提取模态参数的一般损伤识别方法相比，二次协方差矩阵包含结构振动的更多和更高阶模态信息。本文利用结构损伤前和损伤后的二次协方差（CoC）矩阵参数的变化比，对只基于振动输出的、环境振动下的结构进行损伤识别。对一个七层框架结构模型进行了数值模拟，首先对不同噪声程度、不同损伤位置和程度的损伤结构进行损伤定位，再结合模型修正法，对结构损伤程度进行识别，展示了该方法的有效性。

Damage Identification under Ambient Vibration Based on Change Ratios of Covariance of Covariance Matrix Components of Structural Acceleration Responses

A new covariance of covariance (CoC) matrix is formed from the auto/cross-correlation functions of acceleration responses of a structure under white noise ambient excitation. The components of CoC matrix are proved to be a function of modal parameters (modal frequency, mode shape and modal damping) only of the structure. Compared to the general damage identification methods of extracting modal parameters, the formulated covariance matrix contains more information, especially the higher vibration modes of structure. Using the change ratios of CoC matrix components, a method of damage identification is proposed for structures under ambient vibration based on vibration outputs only in this paper. A seven-floor frame structure is studied through numerical simulation with two steps (namely, first damage location and then damage extent identification) to demonstrate the efficiency of the proposed method.