Hysteretic behaviour of tubular T-joints reinforced with doubler plates after fire exposure

The hysteretic behaviour of tubular T-joints reinforced with doubler plates was experimentally and numerically investigated in this study. Two specimens were tested to failure under cyclic axial load at the brace end, one under ambient temperature and the other after fire exposure. Specimens with identical material and geometric properties were compared. The failure modes of the specimens were cracking along the weld toe at the intersection of the plate and brace. The results indicated that the hysteretic behaviour and energy dissipation of the joint after fire exposure were smaller than those at ambient temperature. The finite element package ABAQUS was then used to simulate the joint specimens. In a comparison of the hysteretic curve, skeleton curve, energy dissipation and failure location, the simulation and experimental results were in good agreement. The finite element method was subsequently used to carry out a parametric study. Parameters τ and ε had little influence on the post-fire hysteretic behaviour of the joint, but joints with a large γ or small α, β, or ξ values had a low capacity for hysteretic behaviour after fire exposure.