Identification Of Parameters And Seismic Performance Of Large Masonry Historical Buildings

The materials used in historic buildings are mainly masonry and blockwork,which are relatively large in volume and correspondingly heavy and stiff,and prone to cracking and brittle damage under the influence of earthquakes.Based on the characteristics of this type of ancient architecture combined with the existing historical masonry structures,this paper selects a representative historical building,the Pantheon in Italy,as the object of study.On the one hand,the Pantheon is a representative of the ancient Roman masonry dome construction technology,and its structural form has typical significance,while it has an irreplaceable position in the world’s historical and cultural heritage;on the other hand,the Pantheon was built in an older age,and its circular dome structure is not only experiencing brick loss and mutilation,but also cracks in the structure are constantly developing,and the development of structural damage will pose a greater threat to the safety of the entire ancient building The development of structural damage will pose an even greater threat to the safety of the entire ancient building.The current state of damage and the level of safety performance of the circular dome structure of the Pantheon is a key issue that needs to be investigated.Based on the investigation and vibration measurements of this large masonry historical building,this paper combines finite element simulation analysis to investigate the dynamic characteristics,structural physical parameters and mechanical properties of the circular dome of the Temple of the Gods,and to assess its performance under earthquake action,with a view to reflecting the current performance of the Temple of the Gods in real time and providing a reference basis for subsequent repair and strengthening.The main research of the thesis is as follows.(1)The basic overview of the Pantheon is systematically described,and the damage condition and historical reinforcement of the dome structure is analyzed in conjunction with the historical records and the results of the site survey.A finite element analysis model of the dome structure is developed after simplifying the decorative elements of the structure as well as the existing cracks according to the stresses of the structural components.(2)Based on the existing parameter identification method,the adaptive response surface parameter identification method based on radial basis function is improved for the characteristics of large masonry ancient buildings with a large number of structural physical parameters.(3)Vibration tests were carried out on the Pantheon dome structure by means of environmental excitation to identify its modal parameters.On this basis,the main material parameters of the structure and the elastic modulus parameters of the cracks were selected as the parameters to be identified by means of parametric sensitivity analysis method,and the improved method was used for parameter identification.The modified finite element model,which can better reflect the real dynamic characteristics of the dome structure.(4)Static analysis is carried out from the modified dome structure model to study the force and deformation of the structure under the vertical self-weight load.Structural dynamic time analysis is also carried out according to different Chinese and Italian code standards to study the acceleration and displacement response and deformation damage characteristics of the Pantheon dome structure under the action of ground shaking,and to carry out seismic performance analysis on the dome structure.