FaiMec (Failure Mechanisms): a digital workflow for rapid seismic evaluation of local mechanisms in masonry building aggregates at a territorial scale

Masonry buildings lacking box-like behaviour are highly susceptible to out-of-plane (OOP) failure during earthquakes, threatening both occupants and surrounding structures. To address this issue, this paper presents FaiMec (Failure Mechanisms), a rapid-assessment tool developed for the large-scale seismic evaluation of multi-storey masonry buildings. It considers both isolated and aggregate configurations, accounting for their direct influence on the activation of potential failure mechanisms. FaiMec integrates an advanced macro-block model with the established FaMIVE procedure, introducing three key innovations: (i) refined analytical formulations for activating load factors; (ii) explicit evaluation of seismic demand via floor response spectra; and (iii) a minimization procedure based on the capacity-to-demand ratio, enabling robust identification of governing OOP mechanisms. Using data from the CARTIS Building Form, developed by the ReLUIS Consortium and Italian Civil Protection Department since 2014, FaiMec computes load factors for multiple OOP mechanisms and classifies each building’s seismic risk under the Italian "Sismabonus" system, issued in Italy by a Ministerial Decree. The tool was first applied, tested, and validated on buildings affected by bradyseismic activity in Campi Flegrei (Italy), within a framework agreement with the ReLUIS Consortium coordinated by the Civil Protection Department. The paper presents a qualitative description of the procedure and the purpose-built IT application, supported by six case studies highlighting typological features that influence the activation of specific failure mechanisms. Overall, the tool offers an innovative framework for rapid, large-scale assessment of OOP vulnerability in masonry aggregates, overcoming limitations of existing approaches and supporting prevention and civil protection strategies.