Design criteria for beam-to-column connections equipped with friction devices

In the case of steel Moment Resisting Frames (MRFs), the adoption of beam-to-column joints equipped with friction dampers represents an efficient alternative to traditional joint typologies. In fact, the introduction of devices able to dissipate the seismic input energy providing only low or negligible damage leads to significant benefits in terms of structural reparability and resilience. Even though in recent times theoretical and experimental efforts have been made to provide a better understanding of the seismic response of these innovative connection typologies, to date no pre-qualified design guidelines are available. In order to fill this knowledge gap, in this paper, exploiting the framework of the pre-qualification procedures proposed by AISC-358, a precise set of design criteria is set up. In particular, step-by-step design guidelines based on the outcomes of previous research works are suggested. The accuracy of the proposed design rules is verified by means of four experimental tests on full-scale subassemblies of beam-to-column joints which have been designed according to the proposed criteria. The experimental work under cyclic loading conditions has regarded two different configurations of friction dampers: i) friction damper plan parallel to the beam flange or ii) friction damper plan parallel to the beam web. The experimental results highlight the accuracy of the proposed rules which provide beam-to-column joints able to sustain large inelastic rotations demands with negligible damage to the non-dissipative joint components.