Structural Damage Identification Research Based On Element Modal Strain Energy Sensitivity

In recent decades, because the structural damage was not found and deal in time,accidents are common what brought about casualties and economic losses. In order toensure the security of life and structure, minimize damage and avoid disaster, thedamage detection for the existing structure is a great urgency. It is able to quickly andaccurately identify the damage appearing, the damage location and the extent of damage.So that people can repair the structure timely on the purpose of reducing the extent ofstructural damage accumulation and ensuring the normal operation of engineeringstructures. Therefore, Based on the importance of damage detection, this paper firstreviews the research status and development trend of structural damage identification,focusing on the research status of damage detection based on element modal strainenergy and the probability of damage identification method based on Bayesian statistics,and then the main content and ideas were presented in this paper.In this paper, on the basis of the finite element method, modal strain energy and thefirst-order Taylor series expansion, the expression of the sensitivity of structural elementmodal strain energy to the element stiffness damage index is derived. Then using thestructural dynamic characteristic equation, it proposed the structural damageidentification method based on unit modal strain energy sensitivity and then deduced thestructural damage equations, which can identify the location of the damage and thedegree of the damage simultaneously. Then considering uncertainty of modalmeasurement, it elaborated the principle of damage location and quantitation based onBayesian statistics, propose two damage probability identification methods based onelement modal strain energy sensitivity and Bayesian statistics: the first is the damageidentification method based on damage quantitation theory of Bayesian statistics, andthe second is the two-stage damage identification method based on damage localizationand damage quantitation theory of Bayesian statistics. These two methods can not onlyidentify the location of the damage and damage degree, but also can calculate thedamage probability. Though these methods it can get an identification rerult that thedescription of the structure damage is more precise.Finally, with the theory and the methods of the above, the programs of thesedamage detection methods were written on Matlab flat.Then the damage of a simplysupported beam and a continuous beam under several danmage cases were identified. The identification results show that the structural damage identification method basedon element modal strain energy sensitivity can identify the location of the damageaccurately and identify the damage degree with a small error, and it also has a goodanti-noise ability. While the damage probability identification methods based on unitmodal strain energy sensitivity and Bayesian statistics can get a good result for elementstiffness damage index statistics recognition by using a little number of modalmeasurements. Finally, the relevant problems to research further in this paper werepresented.