Methodology for an effective retrofitting strategy of existing masonry buildings: a case study near L'Aquila

The whole Mediterranean area historical heritage is mostly constituted by 'ancient' unreinforced masonry constructions which are particularly vulnerable to earthquakes. Due to the particular attitude to out-of-plane collapse mechanisms, 'ancient' constructions largely contribute to increase the seismic risk. In this paper, a methodology for retrofitting unreinforced masonry buildings, aimed to gradually transforms the 'ancient' masonry building into a 'modern' code-conforming building, is proposed. This approach has been applied to an existing masonry building located near L'Aquila (Italy) and damaged during the 2009 earthquake. The results demonstrate the usefulness of a methodological approach to implement retrofitting actions. Thus, appears more easily to calibrate the interventions as a function of the structural weakness and to quantify the role of each intervention in terms of capacity-to-demand ratio. Moreover, a gradual control of the seismic performance enhancement with respect to the original capacity can be achieved, avoiding high economic costs related to unnecessary interventions.