Dry stone masonry: mechanical characteristics and seismic retrofit

The seismic retrofit of dry stone buildings, typical of the alpine rural architecture in the Ossola Valley (Piedmont - Italy), needs a structural characterization of masonry behaviour. The less invasive seismic retrofit techniques have been analysed in order to preserve the peculiarities of this masonry texture and alpine architecture. Diagonal compression tests were carried out on dry stone masonry specimens, built both unreinforced and strengthened by a specific stitching technique, which was employed to strengthen the Lossetti Tower, a medieval dry stone tower of 13 meters high. The chosen system is a regular mesh of thin ropes, made of basalt fibres, which pass through the masonry thickness and tie blocks together. In this way it was possibile to connect the wall in the transverse direction and to improve the monolithic behaviour of stone masonry structures by a dry and reversible technique.