PSI - Issue 78

Marco Postiglione et al. / Procedia Structural Integrity 78 (2026) 984–991

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amplify inertial forces during seismic events, even if a double symmetry if often highlighted. Despite their relative scarcity in the study area, such buildings are included in the archetypal classification due to their specific seismic implications. few exist typically built in the late 1970s. Each of these shares the common mid-century material and earthquake-design deficiencies, differing in geometry and likely failure mode. These archetypes provide a structured basis for assessing seismic vulnerability and informing the development of typology-specific fragility models, retrofitting strategies, and prioritization frameworks within the broader objective of seismic risk mitigation for school infrastructure. 4. Results and Discussion Most school campuses in the western metropolitan area of Naples consist of buildings with one to three storeys, typically serving primary and secondary education. The inter-storey height usually ranges between 3.0 and 3.5 meters, with slightly greater heights in gymnasiums or auditoriums. This widespread low-rise typology, comprising 1 to 3 storey RC frames, generally corresponds to fundamental vibration periods between 0.2 and 0.6 seconds, a range that may coincide with spectral accelerations inducing substantial seismic demand. A synthesis of the observed vulnerabilities in RC school buildings constructed between 1950 and 1980 highlights several recurring deficiencies, including: (i) inadequate reinforcement detailing (e.g., smooth bars, sparse stirrups, absence of joint confinement); (ii) short-column effects caused by partial-height infills; (iii) irregular plan configurations (L or T-shapes); (iv) large atriums disrupting uniform framing; and (v) dependence on masonry infills for lateral resistance in one direction. Additionally, material deterioration (e.g., carbonation, corrosion) further diminish seismic capacity. Nonetheless, some beneficial attributes are noted. These include: (a) the low-rise mass; (b) regular plan geometries; (c) rigid floor diaphragms; and (d) repetitive structural frames. Compact symmetric layouts behave more uniformly under seismic loading, reducing torsional response and guaranteeing more uniform drift distribution. Buildings such as Archetype A, with double-loaded corridors and symmetric infill distribution, demonstrate favourable seismic characteristics. However, these advantages do not eliminate vulnerabilities associated with poor detailing and soft-storey conditions. Conversely, buildings with irregular plans – i.e., Archetype B or C – exhibit significant seismic weaknesses. Torsional effects, uneven stiffness distribution, and stress concentrations at re-entrant corners amplify seismic demand so damage potential. One-way frame systems - common in older Italian schools - rely heavily on infills, which behave in a brittle manner, shifting demands to inadequately detailed components. Vertical discontinuities are among the most relevant vulnerabilities. Therefore, while typical RC school buildings benefit from low-rise geometry and some regularity, their vulnerabilities frequently dominate their seismic performance, resulting in diffuse damage state. 5. Conclusions This study presented an expert-judgment structural-typological classification of RC school buildings built between 1950 and 1980 mainly based on in-plan configurations and on some architectural features. To this aim, some schools located in the western metropolitan area of Naples are considered as prototypes, which can be considered representative for the whole Italian territory. Based on detailed surveys and archival data consultation, four archetypes were identified, capturing also recurrent features such as number of storeys, infill configuration, and frame regularity. These archetypes reflect common vulnerabilities - e.g., soft-storey mechanisms, torsional irregularities, stripe windows, short columns, and inadequate reinforcement detailing - which significantly affect seismic performance. The classification aligns with national initiatives such as the School-MARS framework, which seeks to integrate empirical data with structural typologies to guide seismic risk mitigation. Empirical evidence, including data from the 2009 L’Aquila earthquake, confirms that pre -code RC school buildings exhibit damage probabilities comparable to unreinforced masonry structures. By establishing an archetype-driven approach, this work contributes to the development of fragility models tailored to the Italian school stock, enabling scalable risk assessment and retrofit prioritization. The findings support a shift from generic RC classifications to typology-specific strategies, promoting more effective and targeted seismic resilience planning, useful for future application and development of fragility analysis.