Development of a yield-line model for endplate connections in fire

Connection designs at ambient temperature generally consider only the initial stiffness and the plastic resistance, whereas ductility and failure modes are more important for connections in fire, as large deformations are generally experienced. This paper describes the development of a T-stub model to capture the behaviour of endplate connections at large deformations, including failure wherever relevant. The model is based on the virtual work principle, which allows it to be easily applied to endplate connections, and considers material hardening after yielding for both the T-stub flange and the bolts. Compatibility between these two components is also maintained. Validation against T-stub tests at both ambient and elevated temperatures shows that the proposed model can predict the behaviour of T-stubs of various characteristics. Comparison with finite element analysis results shows that this model represents the behaviour of endplate connections very well.