PSI - Issue 84

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

718

1. Introduction The assessment of the seismic safety of the public building stock represents a priority challenge globally, with particular urgency in the Italian context where a vast portion of the existing school heritage was constructed prior to the introduction of modern anti-seismic regulations (Grant et al., 2007). Many of these buildings, erected during the post-war building boom, were designed to resist almost exclusively gravity loads (Alashker et al., 2019; Tan et al., 2018) , manifesting severe intrinsic deficiencies such as the lack of ductile construction detailing and a general inadequacy of structural connections (Saler et al., 2021). Awareness regarding the vulnerability of these strategic structures grew drastically following tragic events such as the 2002 Molise earthquake, highlighting the imperative need to protect the school population and ensure the functionality of buildings during emergency and recovery phases (Perrone et al., 2020). Given the vastness of the national building stock, scientific research has focused on the development of multi-scale prioritization procedures to identify the buildings at highest risk and optimize the allocation of limited resources (Saler et al., 2019). These approaches range from rapid visual screenings based on inspection forms and vulnerability sheets at a territorial scale (Saler et al., 2023), to more detailed mechanical assessments integrated into national risk mapping projects, such as the MARS project (Cattari et al., 2024). In this framework, the study of structural response requires rigorous analytical tools. Among these, the N2 Method has consolidated as a standard for non-linear seismic analysis, allowing for the combination of the simplicity of pushover analysis with the rigor of the inelastic response spectrum (Bosco et al., 2013, 2009; Fajfar and Gašperšič, 1996) . The evolution of this methodology into the acceleration-displacement format has further facilitated the evaluation of structural performance, enabling an accurate estimation of capacity without resorting to complex iterative processes (Fajfar and Eeri, 2001). The analysis of the "as-built" state of reinforced concrete frame buildings often reveals vulnerabilities related to planimetric and altimetric irregularities, as well as brittle failure mechanisms induced by interaction with non structural elements, such as the "short column" effect generated by infills (Saler, 2022; Shendkar et al., 2025). To mitigate such criticalities, modern seismic upgrading strategies must move beyond traditional "trial and error" methods, shifting toward systematic optimization procedures that balance structural safety with economic rationality (Dong et al., 2024). Interventions can range from global stiffening measures to targeted local interventions, such as steel jacketing. This latter technique is particularly effective for the rehabilitation of shear-critical columns, as the use of steel jackets allows for a drastic increase in the strength and ductility of non-ductile elements designed in the pre seismic era (Gkournelos et al., 2021; Riyad S. Aboutaha, 1999). Finally, recent trends emphasize the importance of adopting integrated rehabilitation approaches that combine seismic upgrading with energy efficiency improvements. Such a holistic vision not only aligns with European directives on sustainability and environmental impact reduction but also maximizes the value of public investments in essential community structures (Dong et al., 2024; Pohoryles et al., 2022). The present work fits into this research line through the vulnerability analysis and seismic improvement proposal for the "Minervini-Sisti" school complex in Rieti, applying methodologies established in the literature to ensure adequate safety standards in a high-seismic hazard area. 2. Case Study: The Minervini-Sisti School Complex The school complex analyzed in this study is located within the urban fabric of the city of Rieti, a geographical area historically characterized by high tectonic activity associated with the Central Apennine chain. The territorial framework places the site within Seismic Zone 2B, identified as a medium-seismicity area where significant earthquakes can occur, although the municipal territory borders the more severe Zone 2A to the west. The baseline seismic hazard for the project site was defined based on the geographic coordinates (Lat. 42.4046, Long. 12.8553), assuming a nominal structural life (VN) of 50 years and a functional Class III, given its use as a school facility with significant expected occupancy. This characterization allowed for the derivation of response spectra for the various limit states prescribed by current regulations, defining a particularly demanding framework of horizontal actions consistent with the historical seismicity of the Rieti region. The preliminary knowledge phase relied on the examination of archival documentation retrieved from the relevant technical offices. The original structural project dates back to 1974, a period in which national construction practice was governed by Law 1086/71 and Ministerial Decree 30/05/74, regulations that did not yet provide for modern constructive detailing for energy dissipation and seismic ductility. The analysis of the original documents revealed a