Ricerc@Sapienza

The aim of the present work was to investigate the mechanical behavior of orthotropic
composites, such as masonry assemblies, subjected to localized loads described as micropolar
materials. Micropolar models are known to be effective in modeling the actual behavior of
microstructured solids in the presence of localized loads or geometrical discontinuities. This is
due to the introduction of an additional degree of freedom (the micro-rotation) in the kinematic
model, if compared to the classical continuum and the related strain and stress measures. In particular,
it was shown in the literature that brick/block masonry can be satisfactorily modeled as a micropolar
continuum, and here it is assumed as a reference orthotropic composite material. The in-plane elastic
response of panels made of orthotropic arrangements of bricks of different sizes is analyzed herein.
Numerical simulations are provided by comparing weak and strong finite element formulations.
The scale effect is investigated, as well as the significant role played by the relative rotation,
which is a peculiar strain measure of micropolar continua related to the non-symmetry of strain and
work-conjugated stress. In particular, the anisotropic effects accounting for the micropolar moduli,
related to the variation of microstructure internal sizes, are highlighted.