Improvement And Application Of Structural Damage Identification Method Based On Bayesian Estimation

Structural damage identification is a research hotspot in the field of civil engineering.The method of structural damage identification based on Bayesian estimation can well explain the uncertainty in the process of damage identification,so it is more reasonable and more widely concerned.In this paper,an improved scam algorithm is proposed to solve the problem of single component adaptive Metropolis(SCAM)sampling algorithm in Bayesian estimation.Then,the improved SCAM algorithm is combined with the Bayesian damage identification method based on structural response.The likelihood function of structural physical parameters is obtained by acquiring the observed response data of the structure,and the structure is given by Bayesian theory.The posterior joint probability density distribution of physical parameters and the improved scam algorithm are combined to obtain the posterior edge probability density distribution and the optimal estimation value of structural parameters,so as to evaluate the structural damage.Finally,a four-story shear numerical model and a three-story RC frame structure shaking table test model are identified to verify the effectiveness and practicability of the improved SCAM algorithm,and the Park-Ang two parameter damage model is introduced to realize the probability assessment of structural damage level.The main work of this paper is as follows:(1)Markov Monte Carlo(MCMC)sampling method is an important technical means to solve the parameter posterior edge distribution in Bayesian estimation.Scam algorithm,as one of MCMC sampling methods,is very effective in solving the high-dimensional posterior joint probability distribution.However,the research shows that the algorithm is easy to generate repetitive samples,resulting in low sampling efficiency and large calculation error.In order to solve this problem,this paper proposes an improved scam algorithm,in which the expression of the proposed distribution variance is redefined,which makes the Markov chain composed of sample sequence relatively stable,and verifies the accuracy and efficiency of the proposed method through an example.(2)The improved SCAM algorithm is combined with the structural damage identification method based on Bayesian estimation.The likelihood function of the structural physical parameters is obtained by obtaining the observed response data of the structure.The posterior joint probability density distribution of the structural physical parameters is given by using Bayesian theory.Then the posterior edge probability density distribution and the optimal estimation value of the structural parameters are obtained by combining the improved SCAM algorithm.The physical parameters of the numerical model of a four-story shear structure are identified under the condition of cumulative damage.The results show that the proposed method has high effectiveness and reliability.(3)The physical parameters of a three-story RC frame model under multiple earthquakes are identified through shaking table test,and the Park-Ang two parameter damage model is introduced to obtain the probability distribution of damage index,and the probability evaluation of structural damage level is given.The effectiveness and practicability of the proposed method are verified by comparing the recognition results with the actual experimental phenomena.