FRCM composites for the out-of-plane retrofitting of masonry walls

Several earthquakes occurred during the last decades have shown the seismic vulnerability of masonry buildings, typical of Italian and European built heritage. Post-earthquake damage assessment has often highlighted the weakness of masonry walls when subjected to out-of-plane actions, with a consequent partial or total collapse of the building. To this purpose, different strengthening techniques have been proposed in recent years for repairing and retrofitting masonry constructions in order to extend their service life and improve their structural safety. Among them, structural retrofitting with innovative techniques, such as those based on FRP and FRCM composites, is becoming increasingly widespread, thanks to the significant advantages of these materials with respect to the traditional ones. Despite the growing use of these innovative systems, the knowledge about FRCMs when applied on masonry structures is still quite limited, in particular if their out-of-plane behavior is concerned. In this framework, the aim of the present paper is to analyze the out-of-plane behavior of masonry walls strengthened with different types of FRCM composite materials subjected to axial force and horizontal out-of-plane actions. In order to test full-scale masonry panels, a purposely designed experimental set-up was used for evaluating their behavior under seismic actions. Experimental outcomes will be presented in terms of failure modes, maximum capacity and analyzing differences with reference to an unreinforced wall. The availability of results coming from tensile and bond tests performed on the same materials allowed also to evaluate and compare the out-of-plane capacity of masonry walls with the results of simple theoretical models. The experimental campaign, still in progress, is also aimed at obtaining useful data for the calibration of design formulas suitable for this type of strengthening system.