Study on stress concentration characteristics of square bird-beak square-hollow-section T-joints

Stress concentrations, including stress concentration factors (SCFs) as well as their distributions, of square bird-beak square hollow section (SHS) welded T-joints were investigated by experimental and numerical methods. Load cases of chord axial force and brace axial force were separately considered. Results show that stress variations within extrapolation zones of square bird-beak joints can be described as quadric functions. SCFs on the chord are usually greater than those on the brace, and the maximum SCF of bird-beak joints commonly emerge at four hot spots, i.e., Cr-F, Sa-A, Sa-C, and Sa-D. Typically, stress concentrations of a bird-beak T-joint under chord axial force are not very significant, while the SCFs under brace axial force, whose values vary remarkably with varying non-dimensional parameters β, 2γ, and τ, are fairly high. Comparisons between bird-beak and conventional joints show that, for same dimensions, square bird-beak joints can induce lower SCFs than conventional joints, and the SCF differences between them will be amplified when β is decreased. It should also be noted that the maximum SCF of a square bird-beak joint could be higher than that of the conventional joint when β is greater than 0.75. ©, 2015, Editorial Office of China Civil Engineering Journal. All right reserved.