基于位移响应协方差参数变化比和模式匹配的梁结构损伤识别方法研究

Study of structural damage identification based on covariance of displacement response and pattern matching method

使用结构位移响应参数进行结构损伤识别,首先推导和建立了位移响应协方差参数的解析公式,它是结构频率、振型和阻尼等模态参数的函数。通过理论推导发现,在一定损伤程度范围内,位移响应协方差参数变化比值只与损伤位置有关,受损伤程度的影响较小。结合模式匹配法,使用模态置信准则得到各种可能损伤状态下的置信准则值,找出变化比向量最匹配(置信准则值最大时所对应的损伤状态),即为识别出来的损伤。本文对一个三跨连续梁进行数值模拟来验证该方法的有效性。通过算例发现:与损伤单元有关的位移响应协方差参数变化比值最大,相同损伤位置、不同损伤程度时,变化比向量之间具有大于0.99的置信准则值;而不同损伤位置、相同损伤程度的变化比向量之间的置信准则值则较低。最后进行了损伤工况研究,成功识别出了损伤位置,表明该方法是有效的。对于实际工程结构,可以通过位移响应(或加速度积分得到位移)协方差参数变化比值的连续监测来预警结构损伤的发生。本文提出的方法无需结构模型,计算简便,具有较好的工程应用性。

Displacement response is used for damage detection in this paper. Firstly, the analytical formula of the covariance of displacement response(CoD) is derived and established. It is the function of structural frequency, mode shape and damping ratio. It is analyzed that the change ratio of CoD is determined only by the damage location and is affected by the damage extent slightly. Then the pattern matching method is adopted to calculate the modal assurance criterion(MAC) values between the CoD change ratio vector from unknown structural state and those from all possible sorts of structural damage states. Corresponding to the biggest MAC value, the structural state is identified. A three-span continuous beam is studied to demonstrate the feasibility of the proposed method. From the analysis, it can be seen that the biggest CoD change ratio is related to the damaged elements. MACs between the CoD change ratio vectors from the states with the same damage location and different damage extents are bigger than 0.99. However, MACs from different damage locations and the same damage extent are low. Finally, damage scenarios are studied. Damage occurrence and damage location are identified successfully and it shows that the proposed method is effective. For real engineering structure, CoD change ratio can be obtained and monitored continuously. The proposed method does not need the analytical structural model and is easily computed. So it has good performance for engineering application.