Structural diagnosis of the architectural heritage: The key role of historical research

Modern approach to the diagnosis and structural assessment of historic structure involves several aspects, including information resulting from historic documentation. This item is normally far from the traditional procedures for the structural assessment. Nevertheless, the recent versions of the Italian seismic code require the collection of specific historical information to include in the seismic analysis. In fact, the damage surveyed after the 1997-98 earthquakes documented several brittle structural failures due to defects related to the building transformations. When not considered in the intervention, lack of restrains between masonry portions, fragmentary masonry portions or changes of the building technology can trigger damage but also collapse. The paper focuses the main information resulting from bibliographic and historical research based on available source. Furthermore, the paper underlines the importance of a continuous and direct comparison between the collected data and the building itself. The recognizing of potential discontinuities or irregularity of the structural layout, in fact, could require the planning of further controls to support the safety assessment and analysis.