Analysis and evaluations of flat jack test on a wide existing masonry buildings sample

During the last decade the laboratory of the Department of Civil, Architectural and Environmental Engineering of the University of Padova, together with a Spin-Off of the same University, Expin srl, carried out more than one-hundred on site double flat jacks on masonry panels of a relevant sample of North and central Italy existing masonry buildings. Different masonry typologies belonging to different structural classes (housings, religious buildings, castles, towers,.) were tested, and the analysis of the results-grouped by homogeneous sets-highlighted some analogies, especially for two more diffuse masonry typologies, i.e. brick and irregular stone masonry. The clustered analysis of the wide number of data proposed indeed consistent information on the mechanical ranges of each parameter and typologies (referring to the masonry class subdivision proposed by the Italian Standards NTC08), however highlighting a relevant data dispersion. A multi parametric analysis was applied and some critical aspects are reported in the paper. Another topic discussed in this work is related to the technique itself, namely how the test procedure influences the results. The analysis of these data sets allowed highlighting the most representative parameters to take into account during the test and how to operate in order to obtain them.