Multiscale numerical modeling of clay brick masonry under compressive loading

Masonry is generally comprised of periodic arrangement of masonry unit bonded together with mortar. Masonry is a heterogenous material and exhibits orthotropic behavior. In this study, the elastic-inelastic behavior of brick masonry under compressive loading is predicted using Finite Element Analysis (FEA) based homogenization approach. A three-dimensional repetitive unit cell representing English bond brick masonry is adopted for the homogenization procedure. The proposed approach requires elastic properties, peak compressive and tensile stress, and strain at peak stress values of brick and mortar as the inputs. Material non-linearity in brick and mortar is modeled using concrete damage plasticity model present in ABAQUS software. Using the FEA-based homogenization approach, homogenized stress–strain response of brick masonry subjected to compressive loading (both, normal and parallel to bed joint) and shear loading are obtained. Failure of masonry due to progressive damage development in bricks and mortar joints when subjected to compressive loading is studied. A user-defined material (UMAT) code is developed based on homogenized stress–strain curves. This UMAT can be adopted as constitutive relationship for macro scale modeling of brick masonry using ABAQUS software. The performance of the UMAT is assessed by simulating compression test experiments performed on masonry assemblages found in the literature. The UMAT is found to be satisfactory in predicting the behavior of masonry under compression.