Preservation of historic centres in seismic areas: guidelines for investigation on their vulnerabilità/ Conservarea centrelor istrice în zone seismice: Metodologie pentru cercetarea vulnerabilitãþii lor/ Történeti központok reabilitációja szeizmikus zónákban: Javaslatok a sérülékenységük vizsgálatára vonatkozóan

Some historic centres in central Italy were restored after the 1979 earthquake. A subsequent seism which occurred in 1997 revealed that some techniques used in the previous interventions on historic masonry buildings were not successful due to low durability and/or incompatibility between new and existing materials and structures. An extensive investigation on four small typical historic centres in Umbria hit by the 1997 earthquake was carried out and the objectives of the research were: (i) to define a methodology for the vulnerability analysis of historic buildings at the level of the historic centre, (ii) to collect information on the effectiveness of the repair techniques both traditional and new, (iii) to set up databases storing the information useful to prepare rescue plans, (iv) to use the gathered knowledge for the implementation of reliable models for the vulnerability analysis, (v) to prepare guidelines for investigation and vulnerability analysis. The research was based on: the survey of the building typology, their geometry and crack pattern, the masonry materials’ characterisation on site (by nondestructive and minor destructive techniques) and in the laboratory. The output of the research was a database collecting all information of each masonry building containing also an abacus of the most typical and frequent collapse mechanisms, guidelines for architects and engineers concerning the diagnosis investigation.