Full-scale cyclic tests on a stone masonry building to investigate the effectiveness of a one-side application of the composite reinforced mortar system

a Composite Reinforced Mortar (CRM) system applied on the external face of the walls, are herein presented. The CRM system consisted of a mortar coating reinforced with Glass Fiber Reinforced Polymer (GFRP) mesh and injected steel transverse connectors, which connect the separated wythes of the masonry. The aim of the research is to investigate the effectiveness of this strengthening technique. The study concerns two cyclic experimental tests: the first was carried out on the unreinforced masonry building up to a damage level not far from the ultimate limit state. Then, the building was repaired, strengthened with the proposed technique, and tested again. The second test was carried out up to a near-collapse condition. This allowed to evaluate the effectiveness in terms of seismic performances provided by the reinforcement. The cyclic horizontal load, with increasing amplitude, was applied to each of the two longitudinal walls of the building by means of servo-controlled hydraulic jacks pinned to a vertical steel beam. This beam allowed the distribution of the total lateral force between the first floor and roof level, in the fundamental mode shape. The experiments proved the effectiveness of the proposed strengthening method: with respect to the unreinforced masonry building, the resistance increased by 2.4 times, the displacement capacity by 4 times and the total dissipated energy by about 7.2 times. These benefits were due to the GFRP mesh reinforced coating’s capability to prevent the formation of isolated thick cracks, instead promoting a wider dispersion of many closely spaced thin cracks. Moreover, the importance of transverse connectors in preventing the separation of the masonry leaves in the strengthened walls was also clearly observed.