ABSTRACT
The behaviour of steel special moment resisting frames (SMFs) under the seismic events occurred in the last years evidenced a significant loss of resistance and ductility deriving by the premature fracture of weldings. In fact, even though welded moment connections at beam-to-column joints can represent a full strength joint solution theoretically able to provide steel frames with adequate dissipation capacities, the difficulties deriving by the in situ manufacturing of the welds play a basic role leading to a brittle behavior of the connections and, as a consequence, to an unsatisfactory behaviour of the seismic resistant steel frames. From this point of view, bolted connection for beam-to-column joints have to be preferred in seismic-resistant steel frames provided that the joints have sufficient over strength with respect to the connected beam in order to assure the engagement in plastic range of the beam ends rather than the connections. The dissipation capacity of bolted connections in seismic steel frames has been already investigated as an alternative to perimeter welded moment frames (SAC, 1999; Leon, 1999; Faella, Piluso & Rizzano, 2000; Latour, Piluso & Rizzano, 2008; Rizzano, 2006;). In particular, with reference to Special Moment Frames, design criteria able to guarantee a full strength end plate joint have been proposed and validated in (Piluso & Rizzano, 2007) on the base of a numerical simulation and probabilistic analysis.
