An experimental and numerical study on masonry triplets subjected to monotonic and cyclic shear loadings

This paper presents an experimental and numerical study on the mechanical behaviour of masonry triplets subjected to monotonic and cyclic shear loadings. Masonry triplets were constructed with fired bricks bonded together with three different in composition (i.e. cement-to-sand ratios) mortars. Shear tests on triplets show that cyclic loading significantly reduces the peak shear strength (typically around 18%) with respect to monotonic loads, regardless of the mortar composition. The shearing behaviour of the triplets obtained from the experiments were successfully reproduced using an innovative discrete element modelling strategy in which masonry units and mortar were represented by a series of irregular particles (i.e. through Voronoi-shaped particles) with a fictitious random microstructure. Numerical results highlight that cyclic shear strength reduction can be attributed to the progressive formation of cracks in the mortar layers along with the cyclic loading. These observations provide new insight into behaviour of structural masonry and lead to suggestions for improving assessment techniques for masonry structures subjected to combined actions of compression and shear.