The effectiveness of different retrofit solutions on the seismic performance of ancient URM’ buildings

The historical heritage in Italy are mostly made up of ‘ancient’ unreinforced masonryconstructions that suffer high damages and often collapse when subjected to seismic actions, as, f.i.,happened in the last earthquake of central Italy. For these reasons, they contribute largely to the highseismic risk of the country. Ancient buildings are those built up before the first decades of the XX centuryand are characterized by load bearing masonry walls and floors made of masonry vaults or paralleliron or wooden beams. In such constructions, wall-to-wall and wall-to-floor connections almost alwaysare not effective, due to the lack of specific devices (f.i. steel tie rods) aimed to give the building the box-like behavior. Consequently, the seismic behavior is mostly ruled by the out-of-plane mechanisms, thusgiving rise to a high vulnerability.In this paper the seismic performance of an existing ancient building has been evaluated. The buildingis placed in L’Aquila and was been strongly damaged by the earthquake of 2009. The seismic capacity of a case study has been analyzed considering: (i ) the original as-built condition in pre-damaged configuration and (ii) the after-retrofitting conditi ons, with reference to different strategies of strengthening. In particular, the interventions aimed to transform the ‘ancient’ buildings in a ‘modern-like’ masonry buildings and the ones aimed to increase the material resistance have been both considered.The effectiveness of the different adopted retrofit solutions has been evaluated on the base of seismic performance improvement (in terms of PGA) and the damage reduction which can be achieved. The obtained results demonstrate the fundamental role played by interventions aimed to modify the structural configuration of the building and the reduced effectiveness of only increasing the mechanical properties of the structural materials.