PSI - Issue 78

Ingrid Boem et al. / Procedia Structural Integrity 78 (2026) 457–464

464

7. Conclusions The aim of this study was to develop the seismic fragility curves for a representative dataset of 101 masonry school buildings from the Friuli-Venezia Giulia Italian region, comparing the performance of unstrengthened masonry (URM) and masonry strengthened with a Composite Reinforced Mortar (CRM) system applied at both wall sides (RM). To that, the capacity curves of the buildings (global pushover analysis) were drawn by using a simplified analytical-mechanical approach, through the “Firstep-M_PRO” tool, which was adequately adapted to account also for the beneficial effect of CRM on the lateral performances of the masonry walls in terms of stiffness, strength and displacement capacities, according to the experimental evidences. The buildings were categorized into homogeneous sub-typologies (based on the number of floors and construction period) and the median values of resisting ground acceleration associated to the four different EMS98 damage levels, with the respective dispersions, were calculated for each group, to get the fragility curves. The curves thus accounted explicitly for the extrinsic inter-building variability, considering architectonic and geometric features, and masonry types of the real-world scenario. By providing preliminary framework for evaluating the effectiveness of retrofitting strategies on a territorial scale, the results are intended to contribute to the broader objective of supporting data-informed decision-making in the field of seismic risk reduction, also in comparison with other intervention techniques. The former results evidenced that the seismic vulnerability grows appreciably with moving from single to multi-storey structures; also, a tendency of vulnerability increase seems to appear in structures built after World War II, in respect to older buildings. The effectiveness of the CRM application clearly emerges, even though higher benefits resulted for the median resisting ground acceleration related to advanced damage levels of single-story buildings (+100-240%), in respect to that of multi-storey ones (+40-100%). It is however observed that the strengthening effectiveness on multi-storey structures can be optimized by properly calibrating the intervention floor-by-floor, to optimally exploit the ductility reserves of the resisting elements. It should also be noted that this initial analysis is based on the assumption of global response of the structure, but it is also necessary to tackle with potential local out-of-plane mechanisms. However, the investigated reinforcement technique proves effective also in the mitigation of such phenomena. Acknowledgements The research has been carried out under the financial support of the Italian Department of Civil Protection (IDPC), within the ReLUIS-DPC 2022-2024 and 2024-2026 Research Project, which is gratefully acknowledged. References CSLLPP, Consiglio Superiore dei Lavori Pubblici, 2018. D.M. 17.01.2018. Aggiornamento delle “Norme tecniche per le costruzioni”. Italy CSLLPP, Consiglio Superiore dei Lavori Pubblici, 2019. Linee Guida per la identificazione, la qualificazione ed il controllo di accettazione dei sistemi a rete preformata in materiali compositi fibrorinforzati a matrice polimerica da utilizzarsi per il consolidamento strutturale di costruzioni esistenti con la tecnica dell'intonaco armato CRM (Composite Reinforced Mortar). Di Ludovico, M., Digrisolo, A., Moroni, C., Graziotti, F., Manfredi, V., Prota, A., Dolce M., Manfredi G. 2019. Remarks on damage and response of school buildings after the Central Italy earthquake sequence. Bulletin of Earthquake Engineering, 17. Gattesco, N., Rizzi, E., Boem, I., Dudine, A., Gams, M. 2024. Retrofitting masonry piers, spandrels and a building with composite reinforced mortar. In: Proceeding of the 18 th World Conference on earthquake Engineering, 30 th June – 5 th July, Milan, Italy. Giusto, S., Boem, I., Alfano, S., Gattesco, N., Cattari, S., 2025. Derivation of seismic fragility curves through mechanical-analytical approaches: the case study of the URM school buildings in Friuli-Venezia Giulia region (Italy). Bull Earthquake Eng 23, 2611–2646 (2025). https://doi.org/10.1007/s10518-025-02137-6. Grunthal G. 1998. EMS98 - European Macroseismic Scale 1998. Conseil de l’Europe - Cahiers du Centre Européen de Géodynamique et de Séismologie, Luxemburg. Lagomarsino, S., Cattari, S. 2014. Fragility Functions of Masonry Buildings. In: Pitilakism, K., et al. 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