Experimental in situ behaviour of unreinforced masonry elements retrofitted by pre-tensioned stainless steel ribbons

The results of in situ tests carried out on unreinforced and reinforced poor rubble masonry full-scale walls in the earthquake prone Messina (Italy) area are presented and discussed. This experimental research was aimed at the assessment of the in plane shear behaviour of ancient masonry strengthened with an innovative system for masonry and retrofitting of reinforced concrete element constituted by three-dimensional pre-tensioned stainless steel ribbons. A comparison between different strengthening configurations was made in order to characterise the behaviour of masonry panels under shear-compression load, focusing attention on the diagonal cracking failure mode. The effectiveness of retrofitting method in enhancing strength and ductility of poor rubble masonry walls is proved by comparison of the response of the unreinforced and reinforced structural systems.