Study On Seismic Behavior Of Built-in Square Steel Tube Fabricated Concrete Frame Beam Column Joints

Since the reform and opening up,with the development of China ’s social and economic construction and the advancement of urbanization,the construction industry has made great achievements in construction scale and quality,and has become China’s economic pillar industry.The prefabricated building structural system is one of the most advantageous structural systems in greening,low-carbon and industrialization.However,many beam-column joints of prefabricated concrete frame adopt the form of field wet connection,which cannot give full play to the advantages of prefabricated buildings.In order to solve this problem,this paper refers to the connection form of steel structure,designs the beam-column joints of prefabricated concrete frame with built-in square steel tube,makes and tests four joint specimens,and studies the seismic performance and mechanical mechanism of beam-column joints of prefabricated concrete frame with built-in square steel tube through pseudo-static test and finite element analysis of the joints.The main research contents are as follows :(1)Quasi-static tests were carried out on four beam-column joints of prefabricated concrete frame with built-in square steel tube.The test variables were the thickness of built-in square steel tube and the height of steel beam flange.The test phenomena and instrument data were observed and recorded during the test.After the test,the seismic performance of the components and the influence of the test setting variables on the seismic performance of the joints are obtained through the test data.The test results show that increasing the thickness of the built-in square steel tube can improve the bearing capacity of the specimen and the ductility of the joint.However,increasing the thickness of the built-in square steel tube is limited to improve the bearing capacity and ductility of the specimen.Increasing the thickness of the built-in square steel tube can also slow down the speed of stiffness degradation,significantly improving the energy dissipation capacity of the joint;reducing the thickness of steel beam flange improves the ductility and energy dissipation capacity of the specimen.(2)Through the analysis and related research on the mechanical mechanism of the joints,it is concluded that the shear bearing capacity of the beam-column joints of the fabricated concrete frame with built-in square steel tube is divided into three parts : concrete,square steel tube web,section size and strength of steel beam.On the basis of the second,the calculation formula of the shear capacity of the joint is given,and it is considered that the calculation formula is more accurate after comparing with the experimental value.(3)In the finite element software Abaqus,the model construction and calculation of the beam-column joints of the fabricated concrete frame with square steel tube in this paper are carried out.The finite element calculation results are in good agreement with the experimental results.Based on the finite element model,the finite element analysis of other parameters is carried out to provide ideas for the follow-up study of the joint.