On the ductility of bolted steel joints at ambient and elevated temperatures

Beam-to-column joints must be ductile enough to sustain plastic deformation without premature failure when the moment resistance of the joint is less than the moment resistance of the connected beam. In order to prevent premature failure, the Eurocode 3 imposes that the rotation capacity of a joint must be checked if the design moment resistance of the joint is less than 1.2 times the design plastic moment resistance of the connected beam. The Eurocode 3 gives a simple rule for the rotation capacity of bolted joints, based on the assumption that joints designed with that rule are ductile enough to prevent premature failure of the bolts. This paper analyses the Eurocode 3 ductility rule and shows that this rule is in certain cases unsafe and can lead to brittle failure of joints. An alternative rule is proposed for beam-to-column bolted joints at ambient and elevated temperatures.