Structural Damage Detection With Uncertainty Quantification Using Interval Analysis

Structural damage identification is a method to identify the position and the degree of the damage structure by using sensor test data and the inversion calculation, which is now an important part of the structural health monitoring. When the damage identification is applied to the actual structure, it will be affected by load, ambient temperature and the test error of the uncertainties. These uncertainty factors will be prone to false positives, and lead to invalidation of the structural health monitoring. Based on the theory of interval analysis, combined with the genetic algorithm and vector regression model, a solving algorithm of damage characteristics is proposed in this paper. According to the characteristics of the damage index interval overlap rate, the two stage method of structural damage identification is established. Through the introduction of Information-gap(Info-gap) decision model and decision evaluation criteria, we can identify the structural damage position and the degree of the uncertainties without specifying the interval overlap threshold.The main works are summarized as follows:① The interval optimization algorithm based on NSGA-Ⅱis put forward. By using numerical example and finite element model, the interval optimization algorithm are compared with the traditional interval combination method and the interval truncation method. The results show that the interval optimization algorithm can effectively reduce the extension interval in the solving process, and the former calculation accuracy is better than the latter. Moreover, the influences of different parameter on the interval optimization algorithm in NSGA-Ⅱis discussed, which provides a reasonable reference for parameter setting algorithm.② Vector Auto-Regression(VAR) is used to model the acceleration response signal. The main diagonal elements of the VAR model coefficients are selected as the damage characteristic index and They are combined with the interval optimization algorithm to solve the problem of uncertainty of structural damage and to set up a two stage decision process. Through six-story shearing numerical frame example, it verify that the proposed damage identification method is effective.③ With the combination of the Info-gap theory and the interval analysis, the decision model and robust degree model were proposed. Based on the analysis of the physical meaning of parameters in the two models, the Info-gap uncertainty decision evaluation model was established by the feedback function. And the evaluation model was verified by the six-story shearing frame model. The calculation results show that the proposed damage identification method based on Info-gap decision model can identify the structural damage accurately.④ Through increasing mass on a four story steel frame structure, testing in different environmental temperature and using different VAR model order, which simulate the uncertainty of quality, environment temperature and the damage index property extraction. The results obtained by the injury two stage decision method show that under the three kinds of uncertain factors the uncertainty of structural damage identification method can effectively identify the structure damage.