PSI - Issue 78

S. Cattari et al. / Procedia Structural Integrity 78 (2026) 1577–1584 S.Cattari et al. / Structural Integrity Procedia 00 (2025) 000–000

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1. Introduction The safety of schools against natural and man-made hazards is one of the most important concerns for national governments and multilateral agencies worldwide, as demonstrated by increasing risk mitigation efforts being promoted (e.g., Gülkan, 2004; GPSS, 2014; Ventura et al., 2017). In Italy, following the 2002 S. Giuliano earthquake, an effort was made to implement a more comprehensive strategy for the risk mitigation of public buildings. OPCM 3274/2003 mandated seismic vulnerability assessment for all strategic (e.g. hospitals) and critical buildings (e.g. schools), while introducing modern criteria for newly designed and assessment of constructions, along with the seismic classification of the entire Italian territory. Subsequently, significant retrofitting programs were funded in 2003 and 2009, resulting in approximately 1,350 strengthening interventions on strategic and critical buildings, a considerable percentage of which were for school buildings. Notably, the National Prevention Plan, coordinated by the Italian Civil Protection Department (ICPD) (Law 77/2009), allocated around 1 billion euro in 2009, with additional funding since 2018 (Dolce et al. 2021). In line with the previous version and consistently with Eurocode 8, the current Italian building code (Ministerial Decree, 2018) considers three intervention strategies to improve seismic safety: i) Repair or local interventions, ii) Seismic upgrading, with at least a 10% improvement of the as-built safety level, iii) Complete rehabilitation, achieving the safety level of newly designed buildings. For the "Repair or local interventions" strategy, the approach targets a few structural members to address specific deficiencies or damage, without significantly affecting global stiffness. Unlike seismic upgrading (ii) and complete rehabilitation (iii), local strengthening (i) does not require safety checks under current codes. In all intervention types, only ultimate limit states (e.g., Life Safety) must be assessed for seismic performance, except for strategic buildings (e.g., hospitals), where serviceability and damage limitation LSs are also mandatory. For seismic upgrading of schools and hospitals, at least a 60% improvement relative to new buildings is required. Additionally, seismic actions for school design are based on a return period of 712 years, compared to 475 years for residential building. Data from the reconstruction process in the aftermath of the 2009 L'Aquila earthquake indicates a dominant trend in seismic upgrades towards localized interventions for both private buildings (Dolce and Manfredi 2015; Di Ludovico et al. 2017) and public ones, such as schools (Frascadore et al. 2015). Local interventions are often used when seismic upgrading or complete rehabilitation strategies are considered to solve brittle failures, for example involving short columns or beam-column joints in RC buildings. These strategies incorporate supplemental lateral-load-resisting systems, such as shear walls, energy-dissipating devices, base isolation systems or exoskeleton based solutions (Manfredi et al., 2021; Santarsiero et al., 2023). Although such approaches have proven effective in significantly improving the seismic performance of RC structures, they can be invasive and economically demanding. In order to define sustainable retrofit interventions aimed at minimizing environmental, social, and economic impacts throughout an integrated approach, a specific work package WP5 “Integrated and sustainable interventions for existing constructions” has been promoted in Italy since 2017, in the framework of the research agreement between ICPD and its centre of competence on seismic risk, the Reluis (Network of University Laboratories for Earthquake Engineering) consortium. A comprehensive report about the developed solutions can be found in Prota et al. (2024). The same research agreement also focuses on seismic risk assessment at the national scale of different assets. Since 2019, the MARS (Seismic Risk MAps) project (Masi et al, 2021), carried out with the cooperation of the EUCENTRE foundation, aims at updating the national risk assessment by considering residential and critical assets, such as schools (Cattari et al., 2024). In the ongoing 2024-2026 MARS-CARTIS project, the seismic risk of schools is being further updated by including data collection about the most commonly adopted strengthening techniques, aimed at selecting archetypes representative of retrofitted types to be used in seismic risk analyses. In this paper, the first version of the database developed through the joint effort of three research units (RU) is presented: the University of Genova (UniGE, coordinated by Prof. S. Cattari), the University of Basilicata (UniBAS, coordinated by Prof. A. Masi), and the Politecnico di Milano (PoliMI, coordinated by Prof. L. Petrini). The paper describes the data collection procedures that will allow the database to be progressively expanded, with the aim of making it increasingly representative of the entire Italian context. Currently it contains around 40 retrofitted school buildings encompassing both unreinforced masonry (URM) and reinforced concrete (RC) structures. Data available deal with type and strategy of intervention (i.e., local, upgrading and full rehabilitation), performance improvements and actual costs, thus also providing useful information for the development of future risk mitigation programs.