Out-of-plane experimental behaviour of T-shaped full scale masonry wall strengthened with composite connections

Abstract

Abstract The seismic behaviour of existing masonry buildings strongly depends on the type of connections between orthogonal walls and between walls and floors. Recent earthquakes have clearly shown that the most common failure modes of existing masonry buildings involve out-of-plane mechanisms. In these structures, the structural connections are crucial to achieve a favourable distribution of horizontal loads and to avoid out-of-plane mechanisms. In order to investigate on the effectiveness of typical existing structural connections between bearing walls in masonry buildings, an experimental program has been carried out on a full scale T-shape tuff masonry specimen. A weak connection has been designed between the two orthogonal walls of the specimen in order to reproduce common execution practices. Three tests have been performed under the simultaneous application of axial load and monotonic or cyclic horizontal displacements on the specimen in three different configurations: as-built, repaired, and repaired and strengthened with an innovative solution based on the use of composite systems. The strengthening solution consisted of grouted anchors made by hollow CFRP pultruded carbon tubes wrapped with longitudinal and spiral stainless steel fabrics to increase the bond between mortar and tubes. The paper reports the main aspects related to the experimental test setup, the theoretical predictions in terms of strength capacity, the main experimental results at global and local level, and the crack patterns and failure mechanisms of the as-built and strengthened specimen.