Mechanical Performance Analysis Of Prefabricated Steel Tubular Column Connection With Haunch And Rib-reinforced

In the study of fabricated steel structure,the joint is the most important part,and its connection form directly affects the strength,stiffness and stability of the structure,so the study of the mechanical properties of the joint has always been the focus and core of the study of steel structure.The fabricated semi-rigid joints have better ductility and energy dissipation capacity than rigid joints,which greatly reduces the possibility of brittle fracture in the load state,and ensures that they have sufficient bearing capacity while reducing the manpower workload.In order to achieve both construction speed and construction quality requirements.In the design of assembly joints,it is necessary to make disassembly simple and convenient,avoid field welding as far as possible,reduce the influence of residual stress,reduce the consumption of resources,and achieve green environmental protection and energy saving.Most of the assembled joints are bolted,and their bearing capacity and initial stiffness are smaller than that of rigid joints.In order to strengthen the stiffness of prefabricated joints,in this paper,a kind of assembled ribbed and axillary reinforced square steel string joint is designed according to the specification to analyze the pseudo-static force of the side column node and the middle column node with low cycle reciprocating cycle load,and to analyze the influence of the change of component size on the mechanical properties of the joint,put forward the design proposal of this joint,which provides a reference for the research of prefabricated reinforced joint.The surface of the steel tube column of the square steel pipe string welding a short beam with grooves,the rib plate is welded at the slight eccentricity of the column,the axillary plate is welded at the upper and lower axis of the long beam,the upper and lower flange of the long beam is connected with the short beam groove,the upper and lower axillary plate of the beam is bolted with the column rib plate and the upper and lower flange of the long and short beam are bolted,and the long and short beam web plate is bolted through the connecting plate after docking,and the installation can be completed without the installation,this joint assembly is simple and easy to install.As an assembly reinforced joint,it integrates the advantages of semi-rigid joint and reinforced joint,and has certain engineering application value.To analyze the influence of the thickness of axillary plate,length of axillary plate,whether to add axillary plate,joint full welding,column wall thickness and web connection position on the mechanical properties of joints,designed 8 side column nodes and 6 middle column joints,established the finite element model and the low cycle forward reset load is carried out respectively,analyze the mechanical properties of the joints by stress-strain curve,hysteretic curve,energy dissipation coefficient,skeleton curve,stiffness degradation curve and so on.The results show that:Axillary plate length,web connection position and column wall thickness web connection and the thickness of column wall have great influence on the seismic capacity and bearing capacity of the joint,in which the shortening of the armpit plate will reduce the bearing capacity and the energy dissipation capacity slightly;the thickening of column wall makes the bearing capacity of the joint increase greatly,but the energy dissipation capacity of the joint decreases,and the energy consumption of the bolt is not reflected,and its failure form approaches to the rigid joint;the low stiffness of the square steel tube column will lead to the first yield of the column wall during the loading process,so that the stress and strain of the joint are concentrated in the column wall,which does not conform to the design code of “strong column and weak beam”,so the stiffness of the square steel tube column should be given priority in the design to prevent excessive deformation of the column wall during loading;in accordance with the design code of “strong column and weak beam”,the plastic hinge can be moved out effectively,and the superiority of strengthening joint and semi-rigid joint can be brought into play at the same time,which provides the direction of thinking and data reference for the follow-up research of the joint.The assembled ribbed and axillary reinforced square steel string joint can have higher bearing capacity under low cycle reciprocating cycle loading,the optimized designed joint has better seismic performance and can realize plastic hinge outward movement,which meets the requirements of joint design,that joint has better hysteretic performance and energy dissipation ability than the same size full welding joint,and the energy dissipation capacity is slightly lower than that of the non-axillary plate joint,but the bearing capacity is improved.Among them,the deformation of zj-4square steel pipe column of the fully welded joint is too large and there is no bolt buffer,so the slight torsion of the joint leads to the instability of the joint.This phenomenon highlights the superiority of the energy dissipation and shock absorption of the semi-rigid joint and the necessity of using bolt connection for the design joint.If the stiffness of square steel string is not increased,the seismic performance of middle column joint is slightly lower than that of side column joint,and the semi-rigid advantage of joint is more difficult to play.The energy dissipation capacity of the middle column joint is greater than that of the axillary plate joint.