Discrete Element Bonded-Block Models for Detailed Analysis of Masonry

A detailed modelling approach to represent masonry at the meso-scale is proposed, based on the discrete element method, considering the nonlinear behavior of the joints and the units. The fracture of units is represented by the bonded-block concept, in which a random network of potential cracks is created, allowing the progressive development of failure mechanisms. For simplicity, only the 2D case is presented, but the extension to 3D is straightforward. A key component of the proposed model is a framework for a joint or interface constitutive model, including the post-peak softening range, taking into account the experimental fracture energies. In this model, the softening curves in tension or shear are defined by piecewise linear segments, calibrated to reproduce the most common masonry constitutive models. The essential issues involved in the application of bonded-block models to masonry are examined, namely the block shape, either Voronoi polygons or triangles; size; deformability; and the influence of the main constitutive parameters. Uniaxial compression tests are analyzed in detail. The simulation of a well-known experiment of a brick panel under shear shows the good performance of the proposed approach. The investigation results demonstrate the model's capabilities and provide guidelines for its application.