The Out-of-Plane (OP) bending behavior of Un-Reinforced Masonry (URM) walls retrofitted by Steel Fiber Reinforced Mortar (SFRM) coating was investigated by performing in-situ experimental tests on two one-way vertically spanning samples. The latter were part of a two-story full-scale hollow clay block masonry building tested in a previous experimental investigation. The building was provided with single-sided strengthening consisting of a 30 mm thick layer of SFRM coating applied only on the outer surface. Despite the geometrical asymmetry of retrofitting, the reverse cyclic tests highlighted the ability of the sample to attain a very similar OP resistance, irrespective of two loading direction. Moreover, the comparison between the expected OP capacity of the un-strengthened wall and that observed in the experimental tests for the strengthened specimens allowed to appreciate the considerable resistance enhancement resulting from retrofitting.

The results of the OP tests were then compared with the outcomes of 2D non-linear finite element analyses of the retrofitted walls based on the “smeared crack” approach. Considerations about the observed failure mechanisms, resistance and ductility were reported and analyzed. The numerical study was performed to validate the adopted model in view of future studies carried out on different retrofitting configurations.