The limit analysis of macro-elements in masonry aggregate buildings as a methodology for the seismic vulnerability study: an application to Umbrian city centers

The results of an automatic procedure developed at the University of Padova and based on numerical models calculating the accelerations which activate local collapse mechanisms of macro-elements that can develop in historical masonry buildings, are presented: the Vulnus methodology, based on the fuzzy set theory, provides global vulnerability assessments of individual structural units or groups of buildings, as well as fragility curves related to the achievement or overcoming of the limit state of heavy damage. Moreover, Vulnus is able to identify the vulnerability class for each structural unit, as defined by the European Macroseismic Scale EMS98. The EMS98 scale separates the definitions of building typologies from the corresponding vulnerability class and thus from the expected behaviour in case of seismic event: in this way, it provides a common framework for the evaluation of seismic vulnerability and the estimation of the damage of buildings on a large scale. Analytical applications for buildings sampled in two historic centres in Umbria located in seismic area (Campi Alto di Norcia and Castelluccio di Norcia) characterized by various building typologies and different levels of aggregation of the buildings are presented.