Microstructural model for dry block masonry walls with in-plane loading

Constitutive equations are obtained for dry block masonry walls loaded by in-plane forces. A microstructural approach is followed to account for the displacement jumps taking place at small flaws inside the blocks as well as at block edges. Displacement jumps are treated, for a sufficiently large sample of masonry, as strain contributions by means of a proper homogenization procedure. Blocks are modelled as elastic solids containing small frictional cracks distributed at random. The strain contributions due to displacement jumps occurring at block edges are shown to be both contained and uncontained. After discussing the former, the limiting stress conditions for the mechanisms of uncontained strains become active and the corresponding flow laws are analysed. Under the restriction that strains are not so large that the block assembling is substantially changed, the derived constitutive equations can be employed in continuum analyses of masonry walls.