Design of CHS brace-to-H-shaped chord T-joints under axial compression

This paper presents a finite element model of circular hollow section (CHS) brace-to-H-shaped chord T-joints under axial compression, which was verified by the corresponding test results. The parametric study was carried out to reveal the failure modes and plasticity propagation of tubular joints. The effects of CHS brace diameter to H-shaped chord flange width ratio (β), H-shaped chord flange width to thickness ratio (2γ), and CHS brace to H-shaped chord flange thickness ratio (τ) on the ultimate strengths of tubular joints were evaluated. The typical failure modes were obtained from the finite element analysis, which include local buckling failure of CHS brace (LBFB), local buckling failure of flange and web of H-shaped chord (LBFF+LBFW), and local buckling failure of CHS brace and H-shaped chord flange (LBFB+LBFF). The validity range of main geometric parameters was recommended to be β≥0.7, 2γ=20-30, and τ=0.25-0.5. The design equations are proposed by using multiple linear regression for CHS brace-to-H-shaped chord T-joints under axial compression based on the current design rules given in the Eurocode 3. Current Eurocode 3 is dangerous for predicting the ultimate strengths of CHS brace-to-H-shaped chord T-joints under axial compression. It is shown from the comparison that the joint strengths calculated using the proposed design equations agreed well with the finite element analysis results, which means the proposed design equations are verified to be accurate.