The Lossetti Tower in Beura-Cardezza (Italy): Structural Assessment and Rehabilitation of a Historical Dry Stone Masonry Building

Abstract

Dry stone masonry (DSM) is an ancient construction method widely used for vernacular and military buildings in rural and mountain regions. The use of this particular method is due to the large availability of natural stone that characterized these areas. The consolidation of DSM buildings is a challenging issue: in fact, this kind of masonry proved to be scarcely reliable under eccentric and horizontal loads and in absence of elements that are long enough to cross the masonry in its thickness. However, there are very few techniques that can preserve the peculiarities of a masonry texture. This paper presents the design approach that was used for the structural rehabilitation of the Lossetti Tower, a medieval DSM watchtower located in Beura-Cardezza (Italy, Piemonte Region). First, a preliminary research on the building was conducted. Secondly, to better understand the masonry quality, both a 3D laser scanning geometric survey and a technological study of the masonry typology and texture of the tower were executed. Thirdly, to evaluate the mechanical behaviour, a diagonal compression test on the DSM specimens was performed. Finally, after a structural assessment, was developed a tailored design of the strengthening intervention by using the technique of continuous basalt fibers stitching. The proposed system consists in creating a mesh of basalt fiber ropes, that passes through the masonry thickness and ties the blocks together. This system also allows to connect the wall in the transverse direction and to improve the monolithic behaviour of masonry panels in perfect compatibility with the original materials and it was preferred to the more invasive ones also for its reversibility.