PSI - Issue 78

Laura Giovanna Guidi et al. / Procedia Structural Integrity 78 (2026) 2154–2161

2161

(N) resulting from linear analyses with the LSLS design spectrum were identified and subsequently compared with the corresponding resistance domains. The verification consists in checking whether the acting point (M, N) lies within the interaction domain. The analysis showed that the lowest ζ values occur at the upper levels, particularly for 30×30 cm columns. For the most critical case evaluated , the resulting ζE value is 0.33. Conclusions The paper addresses the seismic vulnerability of a complex reinforced concrete school building. Dating back to the 1970s, it was originally designed for gravity loads only, prior to the introduction of seismic design codes. A nonlinear static (pushover) analysis was performed for the seismic assessment of the case study. The building has a courtyard layout, organized around a central wide covered atrium. Despite its large footprint, the structure does not include any seismic joints. Given the complexity of the structural configuration, the modeling of Building Block A was developed using three different configurations: independent three-dimensional models for each of the four structural units (Body 1, 2, 3, and 4), created with CDSwin software, and global models of the entire complex. This integrated approach allowed for an accurate representation of both local and global structural behaviour. Each structural unit consists of unidirectional reinforced concrete frames arranged along the transverse direction of the unit. This structural characteristic results in a clear vulnerability in the longitudinal direction, as confirmed by the results of the modal analysis — for example, for the CDSwin model of Body 1, the fundamental vibration period is approximately 3.93 seconds. The presence of connections between the different units through pedestrian bridges significantly improves the redistribution of horizontal actions, contributing to the overall stability of the system. Each unit, in its weak direction, is supported by an adjacent unit that features frames along that same axis, which for the latter represents its strong direction. In addition, certain secondary elements also play a role — most notably, the infill panels. Although not primary structural members, they contribute to a considerable increase in global stiffness. Acknowledgements The support given by ReLUIS consortium is acknowledged. Topics of WP15 – Seismic Isolation and Energy Dissipation Control Systems are the focus of the activities, into DPC-ReLuis 2024-2026. The Authors would like to express their gratitude to Arch. Marianna Pedalino and Eng. Pasquale Gaudino (Città Metropolitana di Napoli, Dirigenti della Direzione Tecnica Scuole), and Arch. Annarita Marciano (Città Metropolitana di Napoli, Direzione Tecnica Scuole, Responsabile del Procedimento per l’intervento in oggetto) . Thanks to Eng. Francesco Aversano for his valuable contribution to structural modelling and analysis. References Brandonisio, G., Guidi,L.G:, Camarda, G., Sorrentino, P., De Luca, A. (2023 -a ). “Hybrid strategy for the seismic retrofitting of existing building s through Base Isolation System”. Procedia Structural Integrity, Volume 44, 2023, Pages 1292 - 1299, ISSN 2452 - 3216, https://doi.org/10.1016/j.prostr.2023.01.166. Brandonisio, G., Guidi, L.G., Michelino, D., Sorrentino, P., De Luca, A. (2023). “Seismic retrofit of an existing important building of the 60’s through a hybrid strategy”, Procedia Structural Integrity, Volume 44, 2023, Pages 1316 - 1323, ISSN 2452 - 3216, https://doi.org/10.1016/j.prostr.2023.01.169. Brandonisio, G, De Luca A. 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In: XIII Convegno ANIDIS Legge 64. Provvedimenti per le costruzioni con particolari prescrizioni per le zone sismiche. Measures for buildings with special requirements for seismic areas, Italy. Gazzetta Ufficiale 2 Febbraio 1974 n.64. Pinto MR. L’osservatorio e l’anagrafe dell’edilizia scolastica per la programmazione della manutenzione. TECHNE: J Technol Architect Environ 2015.;9. Naeim F, Bhatia H, Lobo RM. Performance based seismic engineering. The Seismic Design Handbook: Springer; 2001. p. 757 – 92. Sorrentino, P., Guidi, L.G., Brandonisio, G., De Luca A. (2023). “Seismic vulnerability of gravity load design r.c. buildings of 1960s in low seismic areas”. Procedia Structural Integrity, Volume 44, 2023, Pages 1308 - 1315, ISSN 2452 - 3216, https://doi.org/10.1016/j.prostr.2023.01.168.