Mechanical Behavior Analysis Of Outer Sleeve Square Steel Tube Columns And H-shaped Steel Beams Connection Joints

The beam-to-column bolted joints can be welded in factories.The installation of the components can be completed only by tightening the bolts on the construction site.The adverse effects of weld quality and welding residual stress on the mechanical properties of the joints can be avoided.The ductility and bearing capacity of the joints can be improved,and the low carbon environment protection can be achieved.The difficulty of quality control.Therefore,the research on full bolted beam-to-column connections has become increasingly prominent.The main research work of this paper includes:1.In order to better meet the performance requirements of steel beam-column assembly and connection in construction site,a new type of sheathed tubular beamcolumn assembly joint is designed and constructed based on the analysis of the performance of various joints and the related research results at home and abroad.In order to ensure the reliability of this study,the finite element modeling and analysis method is described in detail,and the validity of the finite element simulation method is verified by the existing experimental data.2.In order to more intuitively analyze the failure process,stress distribution and working mechanism of the new outer sleeve tubular beam-column assembly joints,based on ANSYS finite element platform,this paper designs and manufactures two new types of joints,a total of 12 new joint models.Considering the material,geometry and contact state of the model,the precise finite element model of the joint is established.The 12 node models are simulated by monotonic loading,and the loading mode is the step-by-step loading mode of beam end displacement.The static and mechanical properties of the new type outer sleeve beam-column assembly joints are analyzed from the stress characteristics of the joints and the stress and failure modes of the components.The roles of square outer sleeve and H outer sleeve in the working process of the joints are obtained.From the geometrical and material aspects of the new outer sleeve tubular beam-column assembly joint model,the main factors affecting the joint stiffness(including initial stiffness)and bending capacity,and the static and mechanical properties of the joint under different joint parameters such as the change trend of moment-rotation(M-theta)curve are analyzed.3.The seismic performance of the new outer sleeve tubular beam-column assembly joints is studied and analyzed.The 12 node models were simulated and analyzed under low cycle loading.The failure modes,hysteresis curves and skeleton curves of each node model were obtained.The seismic performance indexes such as bearing capacity,stiffness degradation curve,ductility and energy dissipation coefficient were determined.Finally,the structural parameters of the new type joints are analyzed,and the effects of the parameters such as the thickness of the sleeve,the wall thickness of the square steel tube column,the length and thickness of the H-type sleeve,the thickness of the flange of the beam and the selection of materials on the hysteretic behavior of the joints are studied.The results of numerical simulation show that the hysteretic curves of the new outer sleeve tubular beam-column assembly joints are stable and full,the stiffness degradation is stable,the ductility and energy dissipation capacity are good;the thickness of square outer sleeve,the length and thickness of H outer sleeve,the flange thickness of steel beam and the wall thickness of square steel tubular column all have certain effects on the seismic performance of the new joints,of which the wall thickness of square steel tubular column has the greatest impact.4.Based on the finite element analysis data of the joints,the moment-rotation(Mtheta)curve and load-displacement(P-_)curve of the joints are drawn,and the initial rotational stiffness and flexural capacity of the joints are obtained.It is known that the joints are semi-rigid joints.Based on the superposition principle of small deformation,a simplified method for calculating the initial stiffness of assembled outer sleeve beamcolumn joints is proposed,and the mechanical model of the components in the joint area is established.When calculating the bending capacity of the assembled outer sleeve tubular beam-column joints,the bending resistance of the joints and the shear resistance of the joint area are considered.According to the principle of "strong shear and weak bending",the calculating method and process of the bending capacity of the outer sleeve tubular square steel tubular column and H-shaped steel beam joints are put forward.By comparing and analyzing the theoretical calculation and numerical simulation results of the new type of sleeve-type beam-column connection,it can be seen that the simplified calculation method of initial stiffness of sleeve-type beam-column assembly joints and the calculation method of flexural capacity of joints are more reliable.