Strengthened thin clay masonry infills: In-Plane and Out-Of-Plane experimental tests

Clay masonry infill walls have shown brittle behavior during recent earthquakes due to the combination of in-plane and out-of-plane actions. These negative aspects are even more pronounced in thin infill walls, often characterized by masonry units with high void ratio, horizontal holes and low compressive strength. Thin masonry infills are typical in existing R.C. frames and extensively used in current construction prac-tice to build internal partitions. This work presents the results of eight full-scale tests on RC infilled frames (one-bay, one-story) with three different types of strengthened thin clay masonry panel. The first strengthening type is characterized by the application of a bi-directional basalt mesh embedded in a special geo-polymeric plaster. The other two strengthening solu-tions consist of applying a fiber-reinforced lime-based plaster, and one of them is also provided with an additional bi-directional basalt mesh. The specimens have been test-ed firstly imposing increasing in-plane cyclic displacements at the frame top beam until reaching pre-determined drift levels, and secondly monotonically loading the infill in the out-of-plane. In particular, to investigate the relationship between the out-of-plane strength reduction and the in-plane damage, out-of-plane tests have been performed at three different in-plane drift levels: 0% (un-damaged), 0.5% and 1.2%. The results are discussed and compared taking an unreinforced masonry infill, tested in a previous experimental campaign, as a reference. Experimental evidences prove the effectiveness of the strengthening solutions in reducing infill damage and, there-fore, in increasing both the out-of-plane strength and deformation capacity. Further-more, the bi-directional mesh positively influenced the failure modes, avoiding the brittle out-of-plane collapse, which conversely characterizes the behavior of thin un-reinforced masonry infills.