Inverse Analysis Of Physical And Mechanical Parameter Of Ancient Pagoda Based On Modified Response Surface-Genetic Algorithm

The combination of native culture and foreign culture lead to the appearance of ancient masonry pagoda,which has great historical and scientific value.Over the past few centuries,the existing ancient pagodas have a certain degree of damage after the earthquake,wind and rain erosion,weathering and even man-made damage,so it is urgent to repair,reinforce and damage detection.In order to evaluate quantitatively the damage degree of the ancient pagoda,simulation software is used to analyze the static and dynamic characteristics of the ancient pagoda.However,whether the calculation results of the simulation analysis are accurate and reliable is closely related to whether the physical and mechanical parameters of the ancient pagoda are scientific and reasonable.In order to get the physical and mechanical parameters of the ancient pagoda with the least error between the simulation and calculation of its dynamic and actual dynamic characteristics,an inverse analysis method of the physical and mechanical parameters of the ancient pagoda based on the modified response surface-genetic algorithm is proposed according to the homogenization principle,the response surface method and the basic theory of genetic algorithm.Firstly,the ANSYS finite element software is used to establish the 3D geometric model of the ancient pagoda,and the Box-Behnken Design(BBD)method is used to design the impact factor test points.The dynamic characteristic of the ancient pagoda corresponding to the design parameters of each group are calculated and the sensitivity of the physical and mechanical parameters of the ancient pagoda is analyzed.Secondly,in the 35% range of the standard values of physical and mechanical parameters of the ancient pagoda,the original parameters are selected with 5% size,homogenizing the data.Establish a numerical model of the parameters to be corrected and the response values.Lastly,based on the measured dynamic characteristics of ancient pagoda,the inverse analysis objective function is established with the least squares rule,and the genetic algorithm program based on Fortran language is used to search the optimal mechanical parameter of the ancient pagoda.Taking Wuhua Temple Pagoda in Yiyang as an example,the proposed method is used to inversely analyze the physical and mechanical parameters of the pagoda.From the sensitivity analysis of the physical and mechanical parameters of ancient pagoda,it is found that the elastic modulus and density of the masonry tower have a significant influence on the dynamic characteristics,and the Poisson’s ratio is second.The inverse analysis method optimizes the parameters of the ancient tower,and the calculation result can converge quickly.Based on the optimal parameters for the positive analysis of the finite element model of pagoda,the calculated values of static dynamic characteristics are basically consistent with the measured values,which proves that the method can quickly and efficiently find the best physical and mechanical parameters of the masonry tower and the results are reliable.The method provides a basis for the repair,reinforcement and health monitoring of similar masonry structure and has an important impact on the protection of ancient Chinese buildings.