The fire behaviour of extended stiffened joints designed for seismic actions

The structural behaviour of steel moment resisting frames (MRFs) is strongly dependent on the beam-to-column joint behaviour. The role of the joints is crucial especially under accidental natural and human induced actions, as in the cases of earthquake and fire scenarios, which can occur subsequently after severe seismic events in urban areas. The study summarized in this paper aims at investigating the fire behaviour of seismically designed extended stiffened end-plate joint by means of finite element analyses (FEAs). The joint performance was investigated considering two scenarios: (i) in the first case the assemblies were subjected only to the fire action; (ii) in the second scenario the fire actions were applied to seismically damaged joints. The numerical results show that the fire action changes the restraining capacity of the joint, and local failure can also occur, especially when fire occurs after severe seismic damage.