Modern industrial plants are highly complex facilities comprising units of various types, connected by physical networks and logical or physical interdependencies. Even slight damages of critical components or structures may lead to disproportionate consequences for the facility and its employees but also for the surrounding environment and population. The risk assessment, mandatory in most cases, is usually conducted by means of either qualitative (rapid and easy to be applied) or quantitative (precise but complex) risk assessment methodologies. The thesis aims at providing a multilevel procedure which is simple-to-update in order to follow the continuous modification of facilities/equipment and is able to rapidly quantify and assess the seismic risk and resilience of existing industrial plants, accounting for the most important metrics that influence the exposure and its temporal evolution. In particular, the objectives of the research are: to develop a multilevel procedure that helps the expert engineers in the application of the PBEE framework, focusing on resilience-based metrics; to develop a simplified, yet quantitative method for the estimation of resilience-based consequences; to develop a model for the prioritization of facilities, in function of the weight each facility has on the Plant's resilience; to develop a model that identifies the critical details, which retrofit is compulsory to achieve a satisfactory resilience of the whole Plant. Such a multilevel framework, represents an enhanced analytical instrument to assess the working condition and the occupational safety in case of a seismic event, providing useful decision-making information for the development of mitigation strategies, leading to an optimization of the economic resources.
