Mechanical Performance Analysis Of T-Stub Connection Between Square Steel Tubular Column And Steel Beam

T-shaped steel connections are generally made of two T-shaped steel and beam-column connections through bolts or welding.The force transmission between the joint members is clear.T-shaped steel connections H-shaped steel beam and H-shaped steel column joints are widely used,while T-shaped steel connections H-shaped steel beam and square steel tube column joints are rarely used.Square steel tube column has the characteristics of larger section moment of inertia,better overall stability and beautiful architecture than H-shaped steel column.In order to provide more technical support for the application of T-shaped steel connection H-shaped steel beam and square steel tubular column joints,this paper studies the mechanical properties of the side column and middle column joints of T-shaped steel connection square steel tubular column H-shaped steel beam by combining theoretical analysis with finite element numerical calculation.The initial stiffness and load-bearing capacity of some side-column joints are calculated theoretically,and the finite element numerical calculation under unidirectional loading is carried out.The finite element numerical analysis of the designed side-column and part of the middle-column joints under reciprocating cyclic loading is carried out.According to the calculation results,the mechanical properties of these joints are analyzed comprehensively.The research results can provide some technical support for the engineering application of T-shaped steel joints of square steel tube columns.The main contents and conclusions of this paper are as follows:(1)The research progress of T-shaped steel to column connections is summarized.The initial stiffness and load-bearing capacity of some T-shaped steel connections with side columns are calculated by theoretical formulas,and the solid model is built by finite element software.Then,the one-way static loading of the joint model is carried out.The results of finite element simulation are compared with those of theoretical calculation.The results show that changing the thickness of T-shaped steel flange has a great influence on the bearing capacity of the joints,while changing the thickness of t-shaped steel web,the connection mode of bolts and the size of column section has a small influence on the bearing capacity of the joints.By comparing the strain energy of each component under unidirectional loading and the stress nephogram of the joint under static loading,it is found that the excessive plastic deformation of T-shaped steel flange is the main reason for the failure mode of the joint.(2)Finite element numerical analysis of side-column joints under reciprocating cyclic loading is carried out.By changing the flange thickness of T-shaped steel,the web thickness of T-shaped steel,the section size of column,bolt diameter and bolt connection mode,nine finite element models are established.By analyzing and comparing the hysteretic behavior of joints,skeleton curve and stress nephogram during failure,the variation of component parameters of joints is analyzed.The results show that with the increase of the flange thickness of T-shaped steel,the bearing capacity and initial stiffness of the joints increase obviously,the hysteretic curve of the joints is bow-shaped and the energy dissipation capacity is better;with the increase of the web thickness of T-shaped steel,the bearing capacity,initial stiffness and energy dissipation capacity of the joints increase,but the increase is small,so it is suggested that the bearing capacity of the joints meet the design requirements.Under the load requirement,the thickness of T-shaped steel webs is not too thick;the change of column section size has little influence on the bearing capacity and energy dissipation capacity of joints;the bolt type has obvious influence on the energy dissipation of joints.When the bolt connection is adopted,the equivalent viscous damping coefficient of joints is small and the energy dissipation capacity is poor,but the bearing capacity of joints does not decrease significantly.(3)Finite element analysis under cyclic loading is carried out for the designed high-strength bolts and the mid-column joints connected with elongated bolts.The hysteretic curves,skeleton curves and stiffness degradation of the joints are compared and analyzed.The results show that the hysteretic curves of the mid-column joints connected with ordinary high-strength bolts are shuttle-shaped,with full curves,large equivalent viscous damping coefficient and good seismic performance.However,the hysteretic curve of the middle column joints with elongated bolts is bow-shaped.Because of the deformation and slip of the tension bolts,the point hysteretic curve has obvious "pinch" phenomenon.The equivalent viscous damping coefficient is small and the energy dissipation capacity is poor.The bearing capacity of ordinary high-strength bolted connections is obviously higher than that of long-to-pull bolted connections.Generally speaking,the bearing capacity of ordinary high-strength bolted connections is better.