| In recent years,China’s construction industry has developed rapidly,and the annual new construction area ranks first in the world.The mainstream extensive production mode can no longer meet China’s energy conservation and environmental protection development policies,so the prefabricated building with high production efficiency and environmental friendliness has been vigorously promoted by the state.For the prefabricated reinforced concrete frame structure,the structural integrity using wet connection can achieve the effect of "equivalent cast-in-place",which has good seismic performance,but there are shortcomings such as complex construction and difficult to guarantee construction quality.Based on the preliminary research of our research group,this paper proposes an assembled monolithic frame structure using snap-on mechanical connectors,that is,after connecting the precast beams and columns through mechanical connectors,the concrete is poured twice to form a whole,and prestress is applied to the beams.In this paper,a low-cycle reciprocating load test study is carried out on this framework,and finite element simulation and parameter analysis are carried out,and restoring force model is established on this basis,and the main work contents and conclusions are as follows:(1)This paper summarizes the development history and research status of prefabricated concrete frame structures at home and abroad,compares the advantages and disadvantages of different forms of nodes and frames,and proposes a prestressed mechanical connection assembled monolithic frame structure on the basis of the previous research of the research group,and introduces the structural form of mechanical connection in detail.(2)In order to study the seismic performance of the prestressed mechanical connection assembled monolithic frame,two mechanical connection assembled monolithic frames and one cast-in-situ frame were designed and produced,both of which were one-span 1/2 scale specimens,and the low-cycle reciprocating load test was carried out,the loading process and failure mode were described in detail,and the test phenomenon and results were analyzed and summarized.The results show that the three frames are typical beam end failures,which meet the design requirements of "strong column weak beam,strong joint weak member".The bearing capacity of the monolithic integral frame of the mechanical connection assembled is almost the same as that of the cast-in-place frame,and the energy consumption capacity and ductility are slightly lower,but it meets the requirements of the specification;The application of prestress can delay the occurrence of cracks,reduce the crack width,and significantly improve the strength,stiffness and deformation recovery ability of the frame specimen.(3)The finite element software ABAQUS was used to simulate the prestressed mechanical connection assembled monolithic frame,and the results showed that the failure morphology and skeleton curve were consistent with the experimental results.On this basis,the parameter analysis is carried out,and it is found that when the effective prestress is less than 0.6fptk,the bearing capacity and stiffness of the frame can be improved by increasing the effective prestress,and the increase of concrete strength grade,beam longitudinal reinforcement ratio and column longitudinal reinforcement ratio can significantly improve the bearing capacity of the frame.When the axial compression ratio is less than 0.45,increasing the axial compression ratio can improve the bearing capacity and initial stiffness of the frame,but reduce the ductility.(4)Based on the experimental and finite element simulation results,the restoring force model of the prestressed mechanical connection assembled monolithic frame was established.It is found that the calculation results of the restoring force model established in this paper are consistent with the experimental results,which can provide reference for subsequent theoretical research and practical application. |
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