Derivation of elastic and inelastic characteristics of non-periodic masonry using homogenization techniques and micro-modelling approaches

The present study is aimed to develop an ad hoc four-steps procedure, based on the use of Digital Image Processing (DIP) techniques, homogenization methods and micro-modelling approaches, able to provide an effective tool for characterizing the mechanical properties of non-periodic masonry. More in detail, after creating, through a DIP technique and automated procedures, a finite element mesh from the Red-Green-Blue (RGB) image of a real masonry wall with non-periodic texture (Step 1 and Step 2), a homogenization method, which considers the properties of each masonry constituent (stone units and mortar joints), is used to derive the main elastic characteristics of a homogeneous continuum equivalent to the random masonry (Step 3). Specifically, this estimate can be achieved following the test-windows method based on the use of least-sized partitions subjected to boundary conditions in terms of displacements or stresses until a chosen convergence criterion is fulfilled. The non-linear response is then accomplished by means of a micro-modelling approach (Step 4). To this end, a threedimensional finite element (FE) analysis can be therefore developed to characterize the main inelastic material parameters of the random masonry. Lastly, as a benchmark of the method, the proposed procedure has been validated against the laboratory outcomes obtained from a previous experimental campaign on non-periodic masonry walls.