A steel jacketing rc beam-column corner joint strengthening system

The results of cyclic experimental tests on full-scale corner beam-column joints, retrofitted with the system SIS.MI.CA., based on the application of a metal insert, are presented herein. Both unretrofitted and retrofitted specimens were tested, with the aim to study the effectiveness of this technique in increasing the capacity of beam-column joints designed only for gravity loads and thus characterized by structural deficiencies typical of the 70’s such as the use of smooth bars and inadequate reinforcement detailing (lack of stirrups in the joint panel and hook-ended anchorages). The tests results show that with SIS.MI.CA. it is possible to strengthen the joint, avoid shear collapse, increase the joint bearing capacity of about 20% and reach a ductility doubled with respect to the unretrofitted joint. In the second part of the paper the description of an electronic sheet for the design of the corner joint retrofitting intervention with this technique is presented. The designer is asked to input only the geometrical and material characteristics of the elements converging in the joints. The sheet deals with the verification of the unretrofitted joint, the design of a suitable insert geometry and the verification of the elements necessary to apply the insert.