PSI - Issue 78

Elisabetta Bonaguro et al. / Procedia Structural Integrity 78 (2026) 1016–1023

1023

6. Conclusion In this paper, FEM modelling of retrofit strategies in urban masonry clustered buildings are addressed through a novel approach which includes diaphragms with different stiffness properties, namelyan unreinforced configuration with a single sheathing-timber floor and a strenghtened one featuring a rigid ribbed concrete slab. The proposed retrofit configurations aim to represent possible real scenarios, involving parts of a single units, parts of the cluster and its entirety. For partial strengthening on asingle SU, the DIANA software highlights damage mechanisms typical of post earthquake scenarios: the results become worse the more the stiffening is localized. For retrofit involving the full cluster, local mechanisms and overall displacements are affected by the insertion of rigid floors, seeming capable of preventing out-of-plane mechanisms of unrestrained walls but limiting the overall displacement capacity: the stiffest configuration results in an 80% increase in base shear compared to the unreinforced model, and a 20% reduction in displacement capacity with relation to an intermediate strengthening solution. When modelling unitary retrofit applied to portion of a two-unit configuration, the perfect connection among the attached units, allowed by the FEM software, obtains a 100% increase in base shear of the unreinforced unit, when the other is retrofitted, compared to the isolated performance. This increase, deemed as unrealistic as the actual connectionsamong units depends on heterogeneous formation processes, would be limited bythe implementation of disconnections (e.g. structural interfaces) among them, something which is expected in the future developments of this work. Acknowledgements This research was funded by the WP5-WP10 ReLUIS Project (Network of University Labs on Seismic Engineering). References Baldessari, C. (2010). In-plane behaviour of differently refurbished timber floors [Tesi di dottorato]. Università degli Studi di Trento. Borri, A., Cangi, G., & De Maria, A. (2011). La risposta strutturale degli edifici in muratura. In C. Donà & A. De Maria (A c. Di), Manuale delle murature storiche (pp. 115 – 183). DEI. Borri, A., & De Maria, A. (2019). Il metodo IQM per la stima delle caratteristiche meccaniche delle murature: Allineamento alla circolare n. 7/2019 . Atti del XVIII Convegno ANIDIS L’ingegneria Sismica in Italia, 15 -19 settembre, Ascoli Piceno. 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