Experimental investigation on out-of-plane behavior of masonry panels strengthened with CFRP sheets

The use of composite materials, in particular Carbon Fibre Composite Materials (CFRP), as reinforcement of both concrete and masonry structures is more and more widespread in the structural rehabilitation and retrofitting of existing buildings, thanks to their excellent mechanical performance combined with lightness and simplicity of application. Since the bond capacity of CFRP-to-masonry bonded joints, with respect to in-plane loads, is generally lower than the composite tensile strength, several methods have been proposed in the literature to increase their structural performance. Among these, CFRP spike anchors showed to be able to effectively increase strength and dissipative capability of CFRP reinforcement sheets. Nevertheless, their use in technical practice is discouraged by the lack of specific rules that adequately support designers. The development of predictive formulas, appearing necessary to bridge this gap, requires an extensive experimental database that highlights the peculiar characteristics of these reinforcements. As a contribution in this field, this paper presents an experimental program concerning the analysis of the mechanical behavior of this type of reinforcements applied to masonry structural elements loaded by out-of-plane actions. The experimental results showed that the effectiveness of such anchors strongly depends on the shape ratio of the specimens.