GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 The vulnerability factors related to the original construction of Faenza buildings are, for example, the presence of windows too close to the top of the walls with the consequent weakening of a very critical portion of the building. The vulnerabilities deriving from transformations are the interventions realized with incongruous materials such as r.c. balconies. The strength factors are first identifiable with traditional anti-seismic devices, such as metallic tie-rods and buttresses, and secondly with an average good quality of the wall texture (mostly made of brick elements). Failures resulting from ground settlements have been systematically observed: they interact with the vulnerability and strength factors by increasing the former's harmfulness and reducing the latter's effectiveness. The results of the on-field survey have been included in a map in which all the factors observed are indicated in each aggregate (Fig. 1). In this way, the map not only allows a preliminary evaluation of the vulnerability conditions of all the aggregates but can also help to identify the priorities for strategic interventions to be promoted by the public authorities. The procedure for defining seismic vulnerability mitigation criteria for Faenza’s historical centre was tested on a sample block performing the so-called “critical survey” (Carocci 2013). This latter was chosen as representative of the characters of the historical built-up context of Faenza and confirmed and clarified the indications deriving from the survey of the whole historical centre. This phase of the study aimed at carrying out an in-depth analysis of the constructional features of the whole urban fabric to identify general design criteria for the conservation and seismic safety of the entire historical centre. Knowing vulnerabilities and strengths at the two levels (comprehensive and detailed) allowed us to identify for the specific recognized problems intervention categories that are explicitly performance-based. They define design criteria – and not technical solutions – to pursue a vulnerability reduction strategy within a conservative approach that is respectful of the original nature of historical masonry structures. Figure 1. Map of the historical core of Faenza in which the type and the number of vulnerabilities and strengths factors are identified for each aggregate.