PSI - Issue 84

Manuel Capogna et al. / Procedia Structural Integrity 84 (2026) 717–724

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This choice is motivated by the need to increase the confinement of the concrete core and to compensate for the lack of adequate stirrups in the beam-column joints, without significantly increasing the global stiffness of the structure, thus avoiding excessive alteration of the dynamic response already analyzed. The application of steel angles and battens allows for the transformation of the collapse mechanism from brittle (shear) to ductile (bending). As supported by scientific literature, steel jacketing ensures an increase in the chord rotation at the Life Safety Limit State, improving the overall deformation capacity of the system (Riyad S. Aboutaha, 1999). Furthermore, this intervention is particularly effective for steels from the 1970s such as Feb38k, whose limited intrinsic ductility can be compensated by the external confinement effect (Gerardo Verderame et al., 2001; Verderame et al., 2011). In conclusion, the integrated approach that led from material knowledge (LC2) to non-linear modeling allowed for an accurate assessment of the vulnerability of the Minervini-Sisti complex. The designed intervention aims to raise the seismic risk indicator above the safety threshold, ensuring adequate protection for the school population. The validity of the strategy is confirmed by the reduction of seismic demand on structural elements and the resolution of the local criticalities identified, steering the structure toward a more resilient global behavior compliant with modern safety standards (Gkournelos et al., 2021). a c

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Fig. 5. (a) Interventions nodes; (b) Interventions frames; (c) Node 17 – 3D view; (d) Node 41 – 3D view.

7. Conclusions and future developments The present study has provided a comprehensive overview of the seismic vulnerability of the "Minervini-Sisti" school complex in Rieti. The methodological approach adopted, starting from a Knowledge Level LC2, highlighted how structures designed in the 1970s present intrinsic criticalities related not only to material quality but especially to the absence of anti-seismic construction details. The pushover analysis confirmed that the system's displacement capacity is limited by brittle failure mechanisms in the columns, with risk indicators below unity that make retrofitting interventions unavoidable. The choice of steel jacketing proved to be the most suitable strategy for increasing local