Study On Structural Damage Identification Based On Wavelet-Particle Swarm Genetic Optimization Algorithm

Civil engineering structures are often damaged during the service process due to the influence of unfavorable factors from the outside world.The occurrence of damage will pose a threat to the safety of the structure.In severe cases,it will lead to structural damage and cause catastrophic accidents.If an effective measure can be taken early to obtain structural damage information,the structural safety status can be pre-warned so as to avoid the occurrence of disaster.Therefore,the study of structural damage identification is of great theoretical significance and engineering application value.On the basis of summarizing the existing methods of structural damage detection,this paper finds that the good localization and multi-resolution characteristics of wavelet analysis method make it unique in identifying structural damage location;The swarm intelligence algorithm has the strict mathematics property which does not depend on the optimization problem itself,and its characteristics such as good global convergence and strong robustness make it have strong ability in recognizing the degree of structural damage.For this reason,this paper combines the advantages of the two methods and uses a two-stage method to study the identification of structural damage location and damage degree.The two-stage method of structural damage identification proposed in this paper is to first identify the damage location of the structure by using the wavelet analysis method,and then use the particle swarm genetic optimization algorithm to identify the degree of damage at the damage location.Firstly,the advantages and disadvantages of the particle swarm optimization and genetic algorithm in solving optimization problems are compared and analyzed.Then combining the advantages of the two algorithms,a theoretical model of the particle swarm genetic optimization algorithm with stronger ability to identify structural damage is established,and the principle of identifying the degree of structural damage is given,and a wavelet-particle swarm genetic optimization algorithm to identify the damage location and damage degree of the structure is established.The damage identification of a single-layer frame structure with multiple damages was studied.First,a finite element model of a damaged frame structure is established,and its strain mode is obtained through dynamic analysis.Then,this strain mode is substituted into the wavelet program to do the wavelet transform.and the damage position of the structure is identified according to the modulus maximum of the wavelet coefficients.On this basis,the objective function is constructed based on the natural frequency and vibration modes of the structure before and after the damage,then the particle swarm optimization,the genetic algorithm and the particle swarm genetic optimization algorithm are used to solve the objective function,and the degree of damage at each damage location of the structure is obtained.Numerical simulation results show that the two-stage damage identification method can effectively identify the structural damage location and damage degree.By comparing and analyzing the effect of the three algorithms to identify the damage degree of the structure,it is found that the particle swarm optimization algorithm has the shortest running time and and the highest recognition accuracy.In order to further verify the effectiveness and superiority of wavelet-particle swarm genetic optimization algorithm in identifying the small damage of complex structures,this method is used to study the damage identification problem of two-story two-span frame structure with multiple damages.Numerical simulation results show that This method can accurately identify the damage location and damage degree of the frame structure.By comparing and analyzing the effect of three algorithms to identify the degree of structural damage,it is found that the superiority of particle swarm genetic optimization algorithm is more obvious in convergence speed,running time and recognition accuracy.Therefore,this two-stage damage identification method has certain reference value for detecting the damage of the actual engineering structure.