Research On Seismic Behavior Of The Assembly Beam-column Connections With Rebars Spliced By Pressed Sleeves

Along with the accelerating of urbanization process,China has vigorously promoted the construction of industrialization.Building energy-saving and environmental protection houses have become the goal and direction of housing construction.Assembled concrete structures have the advantages of high product quality,small impact on the environment and so on.In the assembled concrete structures,the assembled concrete frame structures have a wide range of applications.In recent years,some scholars have done researches on the seismic behavior of assembly concrete frame structures.Based on the existing research results,a type of assembly concrete frame joint with rebars spliced by pressed sleeves is presented in this paper and the seismic experimental and theoretical studies were carried out.The main works and achievements are as follows:(1)Tensile tests on eight groups of specimens with rebars spliced by pressed sleeves were performed,and the influence of staggered angle of steel bar on the tensile behavior of the specimens is studied.The results indicate that different staggered angles have little effect on the tensile properties of the specimen with rebars spliced by pressed sleeve,which means that the rebars spliced by pressed sleeve can be uesd in the assembled structure.(2)Reversed cyclic loading tests on seven assembly beam-column joint specimens and a cast-in-place joint specimen were carried out.The hysteresis curves,skeleton curves,deformation capacity,capacity,stiffness degradation and energy disspation capacity were compared.Furthermore,The effects of longitudinal reinforcement ratio,stirrups spacing and axial compression ratio of column on the seismic performance of the joints are analyzed.The result indicated that seismic performance of assembled beam-column joints with rebars spliced by pressed sleeves were almost equal to that of the cast-in-situ joint.In the tests,the specimens designed as shear failure in the joint core zone or bending failure of the column or flexural failure at the beam fixed end all fail in the expected failure modes.(3)Axial compressive experiments were carried out after the low reversed cyclic loading tests.The axial compressive capacity of columns and joints core zone after low reversed cyclic loading tests were investigated.The results indicate that after the low reversed cyclic loading tests,the specimen joint core zone still has good axial compression bearing capacity.It shows that the joint can still endure vertical load safely after earthquake damage,which embodies the seismic design concept of "strong joint and weak members".(4)Finite element software ABAQUS was use to establish and analyze the models,and the experimental results and numerical results were compared.It can be found that the hysteresis curves,skeleton curves between the experiment and the FEA results have a good degree of agreement.The feasibility of the finite element model used in this paper is verified,and the parametric analysis were carried out on the basis of these models.Based on the cyclic loading tests and FEA results,according to the modified compression field theory(MCFT),the calculation method and shear model of the shear capacity of this joint are established.The influence of different factors on the shear capacity of connections is analyzed.The results indicate that by the MCFT theory can well predict the shear deformation and shear strength of this joint.