Multiscale damage contact-friction model for periodic masonry walls

In the present paper, a multiscale analysis of periodic masonry walls is developed. In particular, a micromechanical analysis is presented for the unit cell, introducing nonlinear constitutive laws, based on damage and friction models, for the mortar and for the blocks. In order to deduce the overall response of regular masonry arrangements to be used for the multiscale analysis, the Transformation Field Analysis (TFA) homogenization procedure is extended to the case of nonuniform eigenstrain. A multiscale procedure is proposed implementing the nonlinear homogenization technique at Gauss point level, in 2D plane state finite element. A nonlocal integral model is adopted in order to overcome problems due to the localization of strain and damage. Numerical examples of homogenization are carried out, comparing the nonlinear mechanical response of the masonry, obtained by adopting the proposed homogenization technique, with the results recovered by evolutive nonlinear finite element analyses. Moreover, numerical applications regarding the mechanical response of masonry structures are performed in order to validate the efficiency of the multiscale approach. In particular, a comparison with experimental data, available in literature, is presented.