Seismic Damage Analysis Of Monolithic Precast Concrete Frame Structure

Under the support of domestic policies,with the progress of construction industrialization,prefabricated structure is facing unprecedented opportunities for development.Different from the cast-in-place concrete structure,once the assembled monolithic concrete frame structure suffers from the earthquake,because of the joint surface between the precast member and the post-cast concrete,in the case of repeated stress,the damage of the joint surface will continue to accumulate and become the weak link of the joint,and the damage characteristic is obviously different from that of the cast-in-place concrete frame structure.When studying the seismic damage of this kind of structures,we can not directly apply the research results of cast-in-place concrete structures,but need to carry out special research.Therefore,it is of great practical value to study the damage assessment of the new generation of assembled monolithic structure.The main research work is as follows:(1)Through the low cycle repeated load test of the reduced-scale joints in the assembled monolithic concrete frame,the test phenomenon and failure characteristics are obtained.At the same time,the numerical model of the joints are established by using the open source software Open Sees for comparative analysis to verify the rationality of the numerical model and provide the basis for the subsequent numerical model of the assembled monolithic concrete frame structure.(2)Based on the joint models of assembled monolithic reinforced concrete frame,a model of assembled monolithic concrete frame structure with three spans and six stories is designed by PKPM.In this paper,the damage model of LV Dagang-Wang Guangyuan is selected,and the calculation parameters are selected through the forcedisplacement curve and moment-curvature curve of each member.The open source software OPENSEES is used to establish the numerical model,and the seismic waves are input by increasing the seismic intensity of the structure,divided into small earthquake,medium earthquake and large earthquake.It can be compared the base shear force,peak displacement at the top and inter-story displacement angle of the assembled monolithic reinforced concrete frame structure and the cast-in-place concrete frame structure.The response of the structure and the seismic local component damage index of prefabricated concrete frame structures can be observed.(3)According to the four weighted combination methods of Park,Du Shuli,Ou Jinping and Chung,the calculation process of the damage value from the floor to the whole of the assembled monolithic concrete frame structure under different seismic intensity is studied.Besides,the plastic hinge generation sequence of assembled monolithic concrete frame structure and the importance coefficient of members are compared,and the influence degree of components on the whole damage is obtained.Firstly,based on the damage index of each member of the frame structure,the damage index of each member to each floor can be obtained and compared by the corresponding weight coefficient assigned by Park and Du Shuli models.Second,it is extended to the damage model of each floor to the whole structure by Park,Du Shuli,Ou Jinping and Chung models.Then,according to the damage index and the seismic damage grade of the structure,the damage of the assembled monolithic concrete frame structure under different seismic intensity is quantitatively evaluated,which provides a scientific basis for the decision-making of earthquake prevention and disaster reduction.Finally,taking the component importance coefficient as the influence degree of the member on the overall damage,it is obtained that the component importance coefficient of the assembled monolithic concrete frame structure is related to the generation sequence of the plastic hinge of the assembled monolithic concrete frame structure.