环境温度影响下基于频率协整的在线损伤识别

频率作为结构损伤特征参数,在实际工程中容易测得且具有较高的测量精度,但同时也常常受到外界环境和运营条件变化的影响,导致在时间序列上的非平稳,给实际工程的健康监测和损伤判别带来了干扰.为解决此问题,引入计量经济学的协整概念,通过非平稳序列的线性组合得到平稳序列,将因环境因素变化导致的结构特征参数非平稳问题转化为平稳问题.首先,详细介绍了ADF(augmented Dickey-Fuller)检验和EG(Engle-Granger)两步法检验,检验结构特征参数的非平稳阶数并计算协整系数;然后,以一个简支梁为例验证了结构频率序列之间的协整关系,给出了环境温度影响下基于频率协整的在线损伤识别步骤;最后,用预应力钢筋混凝土梁与钢桁架简支桥的算例验证了所提方法的有效性和鲁棒性.

Online damage detection based on cointegration of frequencies under influence of environmental temperature

Structure frequency which is always regarded as damage detection feature for its more convenient testability and higher measurement precision is also susceptible to environmental and operational variations. The variations lead to frequency sequence non-stationary and make much disturbances for actual structure health monitoring and damage detection. So cointegration method in econometrics is introduced to deal with the non-stationary problem by the linear combination of non-stationary variables thus the non-stationary problem for structure damage detection feature caused by environmental factor variation is transformed to stationary problem. At first ADF(augmented Dickey-Fuller) test and EG(Engle-Granger) test are detailedly introduced to check non-stationary order of the feature sequence and calculate the cointegration coefficients. Next the cointegration relationship between frequency sequences is verified using a simple supported beam and online damage detection procedure based on cointegration of frequency under the influence of environmental temperature is introduced. At last the validity and robustness of the proposed method are illustrated through a prestressed concrete beam and a simple supported steel bridge.