Calculating the ultimate strength of a tube–gusset KT joint with 1/4 ring stiffener plates

• Published in: Thin-walled structures 2023-04, Vol.185, p.110631, Article 110631
• Main Authors: Qu, Songzhao, Yuan, Jun, Zhang, Quan, Zhang, Bin, Sun, Qing
• Format: Article
• Language: English
• Subjects: Chord axial compression; Stiffener plate; Tube–gusset plate joint; Ultimate strength
• ISSN: 0263-8231; 1879-3223
• DOI: 10.1016/j.tws.2023.110631

In this study, experiments, numerical simulations, and theoretical analyses were performed on tube–gusset KT joints with 1/4 ring stiffener plates, which are frequently used in electrical transmission line towers. The failure modes and mechanisms of the joint were determined to comprise either ‘chord failure’, in which the chord exhibits obvious deformation while the stiffener plate exhibits little deformation, or ‘stiffener plate failure’, in which the chord exhibits obvious concave deformation and the stiffener plate exhibits obvious warping deformation. An increase in chord axial compression caused the ultimate bearing capacity of the joint to decrease, though when the ratio of axial chord force to plastic limit was less than 0.2, this effect of was not obvious. Furthermore, an equation for the ultimate strength of a joint was proposed based on the conservation of energy, which was subsequently verified against test and finite element model results. In this equation, the influence of the chord axial compression on the bearing capacity of the joint is considered using the coefficient β, which is dependent on the ratio of the chord diameter to the chord thickness. Finally, the proposed bearing capacity calculation method was shown to reproduce the numerical analysis results more accurately than the Japanese code or CIDECT code. Thus, the proposed calculation method can be confidently used to guide joint design in electrical transmission line tower projects. •The failure modes of the tube-gusset plate joint were determined to comprise ‘chord failure’ and ‘stiffener plate failure’.•An increase in chord axial compression caused the ultimate bearing capacity of the joint to decrease.•When the ratio of axial chord force to plastic limit was less than 0.2, the reduction effect of was not obvious.•An equation for the ultimate strength of a joint was proposed based on the conservation of energy.