Mesoscopic modelling of masonry using GFEM: a comparison of strong and weak discontinuity models

Abstract

Masonry structures are characterised by their low material cost and relatively simple way of constructing. The computational modelling of these structures remains, however, a great challenge. Two major modelling groups exist: macroscale and mesoscale models. The former approach homogenises the masonry constituents, i.e. the bricks and joints, to one orthotropic material whereas the latter approach models the constituents as separate entities.

In this contribution, two mesoscopic masonry models are presented and compared: a model in which the joints are represented as strong discontinuities and a model in which weak discontinuities are used to model the joints. The bricks remain linear elastic throughout the calculation. Unlike classical models, where the strong and weak discontinuities are modelled, respectively, by interface and continuum elements, the discontinuities are incorporated using the Generalized Finite Element Method. This method allows an in-element embedment of the discontinuities, i.e. the finite element mesh does not need to conform to the masonry joints.

The presented models are compared using equivalent damage models through two-brick, three-point bending and shear wall tests. The simulations are validated with experimental results available in literature. Both governing equations as well as numerical aspects will be discussed. Special attention is given to the handling and number of the enhanced degrees of freedom. Finally, the mesh objectivity of both models is studied.