GNGTS 2019 - Atti del 38° Convegno Nazionale

344 GNGTS 2019 S essione 2.2 to decreasing levels of functionality of its components in terms of spatial and socio-economic equilibrium. The ULC system, as defined, aims at establishing valid references both for the assessment of the current condition of the settlements (in terms of vulnerability of the urban system as a whole) and for the identification of certain levels of urban performance, capable to driving seismic prevention actions (Fazzio and Parotto, 2013). Essentially, for each ULC, the maintenance of some urban functions and the progressive loss of functionality of others are assumed, up to the total crisis. According to the definitions, after a major earthquake, the damaged urban settlement retains the possibility of recovery even in the worst ULC scenario. Indeed, in stating the Collapse Limit Condition (CLC): “as a result of the earthquake, the urban settlement as a whole suffers physical and functional damage such as to lead to the interruption of many of the current urban functions, including residence. However, the urban core conserves the functionality of most of the strategic functions for the emergency and the supporting framework of the recovery strategic functions” (Fazzio and Parotto, 2013, p. 31). Fig. 1 - Schematic representation of the different ULC. Source: Bramerini et al. , 2013a, appx p.2. Elaboration by the authors. Yet, according to the scheme in Fig.1, once the damage corresponding to the CLC is overcome, urban recovery is no longer assured; the only urban performances that can be guaranteed are those crucial for emergency management (ELC). While speaking with respect to ELC (OPCM 4007/2012) it is possible to clearly define what are the strategic functions for the emergency, for the other ULC it is not as immediate to define: first which are the strategic functions for the recovery, and second the criteria to set the thresholds among the different ULC. On one hand, these kind of studies (Bramerini et al. , 2013; Fazzio and Parotto, 2013) try to define a framework of “elements and functions” to analyse urban systems with the aim to explain the recovery process; on the other, recent studies (Basaglia et al. , 2019) changed paradigm, steering the research into a different framework, based on resilience definitions. Starting from this premise, the current research work (that is still at a preliminary stage) aims at answering the main research question: What are those elements and functions that allow an urban system, after a major disaster, to accelerate the recovery process to return at least to its pre-event state? In order to try to respond to this complex issue, the authors started the research activity from a literature review based on resilience theories and applications to urban