Behaviour and design of cold-formed austenitic stainless steel CHS T-joints under brace axial compression

Experimental and numerical investigations of cold-formed austenitic stainless steel (CFASS) tubular T-joints are presented in this paper. The CFASS tubular joints were fabricated by braces and chords with circular hollow sections (CHS). The joint specimens were designed by varying the ratios of geometric parameters (β, 2γ and τ). A total of sixteen CFASS CHS T-joints were tested by applying axial compression through the brace without preloading in the chord. Numerical investigation was then performed including the successful validation of the non-linear finite element model and the subsequent parametric studies. The CFASS CHS T-joints mainly failed by chord plastification. The effects of the β, 2γ and τ parameters on the T-joint strengths were investigated. The design equations for carbon steel CHS T-joints provided in CIDECT, EN-1993–1–8 and the literature were assessed by comparing their predictions with the test and numerical results of the CFASS CHS T-joints. It is shown that these predictions are generally unconservative. New design equations that consider the influences of geometric parameters on joint strengths were proposed. Overall, it was found that the newly proposed equations provided more accurate, reliable and less scattered predictions compared to the design equations in CIDECT and EN-1993–1–8. Specially, the unconservative predictions of 11 % by CIDECT and the unreliable predictions by both CIDECT and EN-1993–1–8 were improved.