Finite element analysis and formulae for stress concentration factors of diamond bird-beak SHS T-joints

A diamond bird-beak T-joint is similar to a conventional T-joint except that the brace member and chord member both rotates 45°. Previous research demonstrated that the diamond bird-beak joint has better static and fatigue behaviour than a conventional joint. Experimental testing has been reported by the authors to determine the stress concentration factors (SCFs) of diamond bird-beak SHS T-joints. This paper fills the knowledge gap through FE analysis, parametric study and proposed SCF formulae for such joints. Three-dimensional finite element (FE) models were developed and validated by experimental data. The FE model was utilized for parametric study on SCFs for diamond bird-beak SHS T-joints to investigate the influence of key non-dimensional geometric parameters β (ratio of brace width to chord width), 2γ (ratio of chord width to chord thickness) and τ (ratio of brace thickness to chord thickness). Finally SCF formulae were proposed for diamond bird-beak SHS T-joints under four loading cases, namely axial force and in-plane bending in the brace, as well as axial force and in-plane bending in the chord.