Research On Nonlinear Finite Element Of Ultimate Strength Of Multiplanar Circular Tubular KT-Joints

Tubular KT-joints is one of the fundamental joint configurations in tubular structures. In the research on the ultimate strength of KT-joints before, it is assumed that section geometry parameters of all branches are the same,meanwhile,chord is not under force and force of different branch is the same.However, it is not consistent with the practice conditions.Analysis of nonlinear finite-element which takes geometric and material to into consideration for ultimate strength of 156 tubular KT-joints is carried out in this dissertation. The influence of nondimensional joints parametersβ₁,β₂ and a on failure mode and ultimate strength of tubular KT-joints is studied. The effect law of these parameters to the ultimate strength of KT-joints is described, and there are three major failure modes: branch strength failure,branch failure and chord local buckling failure. The ultimate strength of the KT-joints goes down under the force of the chord, and changes as the difference of the force ratio of the brances.The effect of KT-joints'welding is important for the ultimate strength of the joints. In the practical engineering, the designing for the tubular joints doesn't include the welding, namely, it is presumed that the welding is no strong than the tubular joints. Eight circular tubular KT-joints considering the welding'effect to the ultimate strength is analyzed, meanwhile, comparing with another eight tubular KT-joints which don't consider the welding'effect.The results showed that ultimate strength of KT-joints considering the welding will be enhanced.Finite-element study about the effect of parameters, welding of the multiplanar tubular KT-joints are researched in the paper, the strength formulae of KT-joints is put award .The research of this paper is meaningful to the consummation of the ultimate strength calculation formulation of circular tubular KT-joints for the code for design of steel structures.