Full-range behaviour of T-stubs with various yield line patterns

Abstract

This paper investigates the full-range behaviour of T-stubs through both experimental and numerical approaches. Nineteen T-stub specimens with six different yield line patterns were loaded to the complete failure. Most of the specimens failed due to rupture of the bolts after significant yielding of the flanges. A new method is proposed to determine the points of initial yielding and ultimate state on a nonlinear full-range force-deformation curve, and by using this method the mechanical properties of the specimens were obtained. Benchmarked against the experimental results, the validities of three T-stub analytical models are examined. None of the models is proven to be able to accurately capture the full-range behaviour of the T-stubs, with the Jaspart model showing a comparatively better accuracy. Finite-element models capable of reproducing the experimental phenomena are developed and are extended to cover all possible failure modes. It is observed that the ratio between the resistances of Failure modes 1 and 3, β, can be used to predict the behaviour and failure mode of the T-stub. The actual β-value dividing Failure modes 1 and 2 is equal to the theoretical value, but that dividing Failure modes 2 and 3 is much smaller than the theoretical value of 2.0. Taking the resistance, stiffness and ductility into comprehensive consideration, it is suggested that a T-stub be designed with a β-value around 0.67 to achieve a balanced design with a good overall performance.