Experimental characterization of “non-engineered” masonry systems in a highly seismic prone area

The mechanical characterization of in situ materials is one of the most important issues in the safety assessment of existing buildings, and – especially for masonry structures – represents a major source of uncertainty. In fact, the possibility of achieving a good “Level of Knowledge” is strictly related to the availability of comprehensive experimental tests on the structures, including destructive testing. In the case of masonry buildings, it is very difficult to extract a representative number of “undisturbed” samples or apply alternative techniques (such as in situ diagonal test) without causing unacceptable damages to the structure. The research work presented in the paper concerns the analysis and experimental characterization of a number of “non-engineered” masonry types commonly present in Calabria (a high seismic prone region located in Southern Italy). The definition of non-engineered is actually referred to self-constructed masonry buildings dated back to the first half of the 20th Century, in the absence of any kind of design and technical control about materials and procedures. The attention has been focused on a number of towns in the Province of Cosenza. Here, a survey has been carried out in order to detect and classify the structural features of the buildings: elements, textures, structural configurations. Afterwards, masonry elements and materials have been experimentally investigated (by testing samples taken on site and manufactured in laboratory). All data have been processed and compared with the Italian and European Standards, in order to derive a reference database for the local masonry building types. In a context where it would be very difficult to directly obtain the required experimental information, the objective is to improve the knowledge about local materials and their mechanical features, providing at the same time a reference methodological approach. In the absence of appropriate information (i.e., of a low level of knowledge) the safety verification and vulnerability assessment turn out to be very conservative. It is thence nearly impossible to provide an effective strategy for the rehabilitation/retrofitting against seismic risk, whereas the systematic, complete substitution of the existing residential housing would became the only solution, which is nowadays a non sustainable option.