Research On Seismic Performance Of New Fabricated Beam-column Joints

A prefab building is a building in which a part or all of the components of a building are prefabricated in a factory and transported to the construction site,where the components are assembled according to a reliable method of connection.Compared with the traditional cast-inplace structure,which has the disadvantages of high energy consumption,high waste and environmental pollution,prefabricated building structure has the advantages of economy,convenience,environmental protection and low energy consumption,which is the development trend of the construction industry in the future.At present,there are many kinds of assembled joints,and the specific structures are very different.In the previous researches on seismic resistance of joints,most of the researches on post-casting joints and welded joints are equivalent to cast-in-place joints,while few researches on bolted joint types are done on assembled joints.Combined with the existing research results,this paper presents a new type of assembly-type joint,carries out numerical simulation analysis of low cyclic loading,and preliminarily calculates the seismic performance of the new joint.The main work and results of this paper are as follows:(1)this paper introduces the new structure and design thinking of fabricated beamcolumn connection node,the node with dark bracket bolts connection mode,using the dark of the higher vertical bearing capacity of the bracket as a bearing component,the beam end embedded bolt connectors,through good ductility bolt through the column will beam fixed,realize the axial force and bending moment transfer effectively.Combined with practical engineering application,the method of component making is given,and the advantages of the node are introduced.(2)In this paper,large-scale finite element software ABAQUS is used for simulation and simulation calculation.A comparison was made between the cast-in-place concrete beam and column joints with the same parameters and dimensions as the fabricated joints,and the section of the beam end section of the fabricated joints was the same as that of the cast-in-place joints.The bearing capacity and seismic performance of the joints under different connection modes of assembled and cast-in-place joints were investigated.The numerical simulation results show that the bearing capacity of the new fabricated beam-column joints under negative loading is equivalent to that of the cast-in-place joints,and the carrying capacity of the new fabricated beam-column joints under positive loading is 20% higher than that of the cast-in-place joints.The stiffness degradation curves of the two models are similar and the fabricated nodes have higher energy dissipation coefficient.Compared with the cast-in-place node,the fabricated node has little difference in mechanical performance and can be regarded as equivalent cast-inplace node.(3)in order to further explore the influence factors of prefabricated node,the node’s dark side length,number of screw connection,screw section size,end plate plate thickness and bolt pre-tightening force different parametric analysis,to explore the impact of these parameters on the bearing capacity and seismic performance,analysis results show that the pillars on axial compression ratio on the stress performance of prefabricated node is small,and the node location screw section size effect on the bearing capacity of the node is larger,increasing the screw area can greatly enhance the bearing capacity of the node.Bearing capacity is no longer significantly affected when end plate thickness reaches 20 mm.The stiffness and bearing capacity of the joints can be improved by applying bolt preloading,but too much bolt preloading will lead to premature buckling failure of the bolt structure.It is better for the bolt preloading to reach 50% of the ultimate load of the screw.Because the structure of the new fabricated node is different from that of the traditional cast-in-place node,in order to facilitate the practical engineering design,the bending moment curve is presented,which can better reflect the mechanical properties of the new node.Through the above research work,the mechanical and seismic performance of the new type of fabricated frame structure beam-column joints are analyzed comprehensively in this paper,which provides a certain theoretical basis for the further improvement and popularization of the new type of joints.