An Alternative Solution to Stirrups for Confinement of Joints into New RC Structures

With the past standard codes, such as the Technical Standards for Constructions (2008) and Eurocode 8, the verification of beam-column joints was done only for structures designed in high ductility class. With the current Italian normative code “Technical Standards for Constructions” (2018), this check became mandatory also for buildings designed in low ductility class and for non-dissipative structures. In this case, inside the nodes, the code requires that the diagonal tensile stress does not exceed the concrete tensile strength: if this condition is not met, it is necessary to insert an adequate confinement reinforcement of the nodes, which is usually characterised by a very small stirrups pitch not always feasible in practice. To avoid this shortcoming, in the current paper, an innovative joint solution made of steel plates is proposed. This alternative system consists of four steel perforated thin plates bolted together at the corner ends and provided with appropriate holes to allow for the passage of longitudinal bars. Satisfactory analysis results obtained from preliminary investigations are a good starting point to continue the study with the aim to launch in the future on the market a new product allowing for both the easier satisfaction of standard checks and the on-site installation faster than that of classic stirrups systems.