Cold-formed stainless steel circular tubular T-joints: Numerical investigation and design

This paper aims to investigate the structural behavior of cold-formed stainless steel circular hollow section (CHS) T-joints with braces subjected to axial compression. The stainless steel materials are austenitic stainless steel (EN 1.4301 and EN 1.4571) and lean duplex stainless steel (EN 1.4162). A finite element model (FE) was first developed and the accuracy of the FE model was validated against the existing test results in terms of axial resistance, failure mode and load-deformation response. An extensive parametric study was then carried out on cold-formed stainless steel CHS T-joints. The key parameters included the ratio of brace diameter-to-chord diameter ( β ), the ratio of brace thickness-to-chord thickness ( τ ) and the ratio of chord diameter-to-chord thickness (2 γ ). The effects of the key parameters on the load resistance of the T-joints were investigated, where these T-joints were failed by chord face plastification. It is shown that the higher β values yield higher ultimate loads while the lower 2 γ values yield higher ultimate loads, and the parameter τ has little effect on the ultimate loads. Furthermore, the applicability of the design equations in the Eurocode, CIDECT, and literature for predicting the strength of the T-joints was assessed by comparing the calculated strengths with the FE results. Based on the findings, the Eurocode is recommended for the strength design of the austenitic stainless steel CHS T-joints. A new equation was proposed for the strength design of lean duplex stainless steel CHS T-joints. The results indicated that the proposed equations provide accurate and reliable strength predictions.