ABSTRACT
A numerical investigation of the structural performance of a fire protected top and seat angle bolted steel connection with double web angles, under thermal and mechanical loading. Both steady-state uncoupled and transient coupled thermal-displacement non-linear finite element analysis have been used. The real, semi-rigid behavior of the connection, imposed by the contact conditions between the various members, has been accounted for using thermal-contact interfaces. A simple numerical scheme, describing the effect of damage of the protection due to elevated temperatures on the response of the structure, is proposed. The reduction of strength of the connection in fire conditions is quantified. Yielding on steel extends to beam, contrary to pure mechanical analysis that appears only on the top-web angles. Even for conservative scenarios, in which fire protection resists thermal actions for a few minutes, the time for the ultimate failure increases from 20% to 40%, in comparison to the unprotected structure.
