Study On Seismic Behavior Of Prestressed Precast Concrete Frame Joints With Steel Sleeve Connection

In recent years,the country vigorously promotes the construction industrialization,and the precast assembly technology is the key technology to achieve the goal of construction industrialization.Precast concrete structure conforms to the development trend of the construction industry and has broad prospects.On the basis of summarizing the research results of scholars at home and abroad,this paper puts forward Prestressed Precast Concrete Frame Joints with steel sleeve connecting beams and columns,namely,post-tensioned unbonded pre-stressed concrete frame joints that are assembled and connected by beam-column steel sleeves and high-strength bolts.In this paper,the seismic performance of this type of joint is tested,and the finite element simulation verification and related parameter analysis are carried out according to the test results.The main work of this paper is as follows:(1)This paper is summarized the research results of domestic and foreign scholars on steel-concrete composite joints and prefabricated concrete frame joints,compares different forms of prefabricated concrete frame joints,improves the prefabricated joint form that the joint steel sleeve is the core and the prefabricated beam column is connected by welding,and puts forward the prestressed prefabricated bolt connection concrete frame joint.(2)Five new joint specimens and one cast-in-place joint specimen are designed and manufactured.The low reversed cyclic loading test is carried out on each specimen.The seismic performance of the new joint is studied by controlling the initial stress of prestressed reinforcement,the thickness of stiffening rib on the beam steel sleeve and the area of longitudinal reinforcement in the beam.The test results show that the bearing capacity and energy dissipation capacity of prestressed prefabricated bolted concrete joint are good,and it has a certain deformation recovery capacity.Under the test load,the damage of the specimen with larger beam reinforcement is mainly concentrated on the beam steel sleeve,while the specimen with smaller beam reinforcement produces bending failure at the beam end,which realizes the outward movement of the plastic hinge.Within the scope of the experimental design,the bearing capacity of the joint increases and the energy dissipation capacity decreases with the increase of the initial stress of the prestressed reinforcement;within the scope of the experimental design,the bearing capacity of the joint increases with the increase of the thickness of the stiffener on the steel sleeve of the beam,but the energy dissipation capacity decreases slightly.(3)The finite element model of the new joint is established by ABAQUS software,and the mechanical properties are simulated.According to the test conditions,the element type,mesh accuracy,material constitutive,interaction and boundary conditions of the joint model are accurately set.The simulation results are in good agreement with the test results,which verifies the accuracy of the test and the feasibility of the finite element method.Carry out expanded parameter analysis on the relevant parameters of the joint,the results show that the increase of stiffener thickness and steel plate yield strength can improve the bearing capacity of the joint,and the increase of longitudinal reinforcement area in the beam may affect the failure mode of the joint.