Guidelines for restoration and improvement of historical centers in seismic regions: the Umbria experience

A methodology of investigation and diagnosis of the built patrimony of historic centres in seismic areas of Italy was proposed by the authors; the aim is to collect an extensive knowledge on the structural typologies and behaviour of historic masonry buildings for the prevention and/or repair of damages caused by earthquakes. Small historic centres or residential buildings in larger centres have been for long time considered as “minor architectures”, but they are meaningful testimonies of the Italian cultural heritage. The results of the investigation also allowed a critical review of the reliability of the analytical models and of the effectiveness of the repair techniques, applied in the past decades. The guidelines emerging from the results of an extensive research are presented. A "minimal" investigation program, which can support the designers in their projects and appropriate mathematical models to study the vulnerability of the structures is suggested.