Mechanical model for the full range behaviour of bolted T-stubs

A new mechanical model for the full range behaviour of bolted T-stubs is proposed in this paper on the basis of a new failure mode classification system which also captures an important failure mode characterised by the rupture of the bolts combined with a moderate level of plasticity in the flange. The proposed model incorporates the abovementioned failure mode in the classic T-stub calculation approach set out in EN 1993-1-8, and also allows for the strain hardening effect of the T-stub flange as well as the strain hardening and necking-induced softening effects of the bolts. Hence, the model is able to accurately capture the full-range behaviour including ductility of the T-stubs featuring any failure mode, using only the geometric and material properties of the T-stubs. The new model is applied to experimental tests on 31 T-stubs, showing good agreement over the full-range of behaviour. Its accuracy is notably higher than the prior models, especially for the ultimate resistance and ductility.