Research On The Bending Rigidity And Gusset Plates Stability Of Tube-gusset K-joints

Nonlinear finite-element analysis of the bending rigidity of the tube-gusset K-joints and the gusset plates stability of the tube-gusset K-joints are researched in this thesis.Nowadays, the researches at home and abroad, which investigate the bending rigidity of tubular joints, are based on the assumption that the elastic-deformation of tubular joints is in a low range, which ignore the influence of axial forces, but emphasize the influence of geometric parameters. But actually, the direction and magnitude of axial forces, which acts on pipes, has a great influence on local deformation and bending rigidity of tubular joints.Therefore, not only the influence of geometric parameters but also axial forces on bending rigidity has been considered in this paper when analyzing the bending rigidity of tube-gusset K-joint, which carried out the bending rigidity of tube-gusset K-joints by ANSYS program. Finally, the influence of every parameter on the bending rigidity is analyzed and explained in detail. Based on a large number of finite-element computations, regression formula of the bending rigidity of tube-gusset K-joints are proposed.In our country, the stability calculation method of truss gusset plate under oblique web member pressure was introduced in appendix F in Code for design of steel structures (GB 50017-2003). In this code, it assumed that the compression zone in the gusset plate was divided into three zones under the pressure, and the stability of each zone was calculated as an axial compression member.In fact, the existence of abdominal bending moment will lead two zones in the edge of the three to subject to compressive stress and tensile stress respectively; In terms of the zone under tensile stress, the existence of ventral moment is beneficial, but negative to the zone under compressive stress. However, it only considers the effect of abdominal axial force, but the impact of ventral moment is neglected in Code for design of steel structures.Therefore, in this paper when analyzing the stability capacity of the node plate of tube-gusset K-joint, the combined effect of abdominal axial force and bending moment was taken into account, and it assumed that the compression zone in the gusset plate was divided into three zones subject to external forces at the same time, then it assumes the compressive district as a axial compression member to calculate the stability capacity, as a result the capacity formula for calculating the nodes plate stability of tube-gusset K-joint under oblique abdominal pressure was introduced. Then, a comparison with the stability capacity calculation formula considering the small deflection theory was carried out.