Finite/discrete element modelling of reversed cyclic tests on unreinforced masonry structures

In the present paper a branch of the FDEM software, developed at the University of Toronto and called Y-Brick, is presented and validated as a useful tool to model the reversed cyclic behaviour of masonry structures of varying levels of complexity. After discussing the available numerical tools for the simulation of the behaviour of masonry, Y-Brick is introduced and described. The program is then used to reproduce a set of experimental tests. The tests consist of applying reverse cyclic in-plane shear to three structures, of different size and complexity, but built using the same materials, with the purpose of simulating the effects of an earthquake. Y-Brick has shown to be able to quantitatively reproduce the experimental results in terms of stiffness degradation, maximum base shear, and energy dissipation with an error of less than 20%, requiring as input information simply the geometry of the specimens, the boundary conditions of the test, and the representative value of the properties of the materials that were used for the experiments. Y-Brick has also shown to be capable of identifying the position of the cracks that form as the structures accumulate damage, providing potential information for eventual strengthening or retrofitting.