GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 and methods of analysis used, in perspective to initiate a new coordinated resumption of the two studies themselves. Moreover, the present contribution aims to underline how the results of preventive seismic vulnerability analysis studies can provide information capable of fostering the activation of seismic risk prevention measures in ordinary urban governance. Faenza’s historical core The study of the historical centre of Faenza lies within the path of seismic risk prevention pursued by Emilia Romagna. Regional Law no. 19/2008 entrusts municipalities with assessing their instruments to reduce seismic risk by adapting their Urban and Building Code (UBC) and updating the Civil Protection Plan. The Municipality of Faenza started the design of its UBC, involving the Department of Civil Protection to test a methodology for assessing vulnerability at the urban scale and the University of Catania to carry out a qualitative vulnerability assessment of the historic core. Moreover, for the first time in Italy, the Technical Office tested the Emergency Limit Condition (ELC) introduced by the Italian Government Ordinance (OPCM n. 4007/2012). The ELC is a municipal scale analysis set up based on the Civil Protection Plans and aimed at guaranteeing the functioning of the emergency management system in the post-earthquake phase. The work on the historical core was carried out in three consecutive phases: (i) the mapping of the seismic vulnerabilities extended to the whole historical centre; (ii) the definition of a survey procedure and its testing on a sample block; (iii) the elaboration of guidelines for the mitigation of buildings’ vulnerability in the historical urban fabric. The analysis of the whole historical centre aimed at the identification of the recurring seismic weaknesses of the urban fabric and the qualitative evaluation of its susceptibility to being damaged by an earthquake. It was performed trying to detect all the factors (constructive, typological, transformative) able to affect, positively or negatively, the seismic behaviour of the urban fabric in its current configuration. The analysis was carried out in four distinct steps: the collection of basic information; the division of the building fabric into aggregates; the on-field survey; and the elaboration of synthesis maps. In a preliminary phase, the information from bibliographic sources revealed some key aspects of the history of Faenza, especially the reconstruction after World War II. Moreover, the cartography provided by the Administration was analysed – compared with aerial photos available on the web – with the twofold objective of identifying the “aggregates” (i.e., blocks) and preparing the base maps necessary for the retrieval of information during the fieldwork. The division of the built fabric into “aggregates” (121 in total) followed the approach of the Italian technical regulations (Min&Inf. 2008), adapting the code’s criteria to the actual situations detected in Faenza. For each aggregate, the on-field survey has been carried out to identify the vulnerability and strength factors of the urban fabric concerning seismic actions, distinguishing between “intrinsic vulnerabilities” (those associated with the original buildings) and “transformation vulnerabilities” (associated to subsequent interventions) (Carocci 2013).