Innovative connections for steel-concrete-trussed beams: a patented solution

The most recent design strategies welcome the adoption of innovative techniques for seismic energy input mitigation, aiming to achieve high dissipation capacity, prevent the structure from collapse and ensure the serviceability of the construction. Friction damper devices have been widely adopted in framed steel structures for decades, while their introduction in different structural types is still under investigation. This paper presents the outcomes of innovative research supported by the industry and conducted on beam-to-column connections of RC structures in which the beams are Hybrid Steel-Trussed Concrete Beams (HSTCBs) and the columns are classical RC pillars. An innovative solution, recently patented, has been found for the mitigation of the effects of seismic cyclic actions on small-sized beam-column joints, typically characterised by a large amount of longitudinal reinforcement due to the small effective depth of the beam. This paper collects the main featuring steps of the innovative research, which has led to the patented solution. The calculation procedure for designing the proposed connection is shown, and the validation through 3D finite element modelling is described. For the structural analysis of the joint, several monotonic and cyclic simulations have been carried out with the scope of investigating different design moment values. The finite element results proved that the patented solution is effective in preventing beam, column and joint from damage and it is suitable for exhibiting adequate dissipative capacity ensured by a flexural behaviour dominated by wide and stable hysteresis loops.