Non-linear behavior of unreinforced masonry walls with different Iranian traditional brick-work settings

The need to preserve and protect the historical buildings around the world has seen the emergence of researches directed toward the analytical modeling of fracture in masonry. The fracturing mechanism in masonry is a complex phenomenon due to existing two brittle materials with distinct material properties. The mechanical behavior of brickwork is strongly affected by the behavior of mortar joints. Mortar joints are the planes of weakness of masonry, especially in old buildings due to the weathering and agedness. On the other hand the orientation of mortar joints affects the fracture pattern of brickwork and causes different types of crack pattern in brickwork settings. Accordingly, the analysis of historical buildings, aimed at structure assessment and restoration, demands an adequate understanding of the mechanical behavior of these different types of brickwork setting and accurate data consisting elastic and inelastic parameters. This paper presents the results of a comprehensive numerical modeling of common types of brickwork settings behavior used in brick-built monuments. Since derivation of an accurate yield criterion for masonry units is usually difficult, there is a higher willingness of using simple plasticity models for practical problems. For better comparison of an-isotropic mechanical behavior of masonry units with these brickwork settings in linear and non-linear phases, numerical modeling of some masonry panels subjected to in-plain compressive and shear loadings are performed using an algorithm based on the Distinct Element Method (DEM). In the DEM modeling, the Mohr-Coulomb failure surface with a tension cut-off is chosen as a constitutive law for both blocks and joints with zero thickness representing mortar bonds. The relations between average normal stress and maximum average shear stress are presented for different brick-work settings taken in this study subjected to monotonic loadings.