Local masonry typologies still unregulated by the Italian Building Code: how to behave? The case of the stone-and-brick mixed masonry in the Marche Region

The safety assessment of existing masonry buildings cannot ignore the correct mechanical characterization of in situ materials. However, this is still a major source of uncertainty due to executive, economic, and conservation issues, that often make difficult the execution of tests and surveys, especially for buildings of historical and cultural significance. In addition to this, in territories characterized by a great variety of materials, techniques, and textures such as Italy, regulamentations and manuals not always offer provisions on certain typologies. To cope with these needs, some previous works introduced innovative methodologies for the numerical estimation of the mechanical parameters of historic masonry walls through qualitative assessment based on visual surveys (i.e., the Masonry Quality Index MQI developed in 2000 by the University of Perugia, Italy). Within this framework, this research aims at roviding first insights about the mechanical characterization of a specific masonry typology, yet still unregulated by the Italian Building Code (NTC18 and CSLLPP n.7/2019), that is the stone-and-brick mixed one. In particular, compressive strength and elastic modulus data have been collected by distinguishing in-situ (sample: 21 double flat-jack tests on 12 different masonry panels) and qualitative measurements (sample: 10 different masonry panels evaluated through MQI) for comparison purposes. All the sampled masonry panels are unreinforced and located in the Marche Region, but the results obtained can be interesting for the entire Italian scene as this specific typology is widespread throughout the national territory. Results reveal a slight discrepancy for the compressive strength data, as the range traced by the in-situ measurements is comparable to the minimum range relating to the MQI method. Conversely, the elastic modulus range obtained from in-situ measurements has such a high dispersion as to compromise an effective comparison with the MQI ranges.