Heterogeneous and continuous models: comparative analysis of masonry wall subjected to differential settlements

The paper presents a comparative analysis of the structural behavior of historical masonry buildings subjected to differential vertical displacements. The work is actually the first step of a wider research into the seismic retrofitting of historical masonry buildings through base isolation systems. In detail, two different approaches to masonry modeling have been adopted: a homogenized model and a heterogeneous model. Homogenization procedures allow modeling masonry as an equivalent continuum but with account for the real configuration of masonry material. Instead, in the heterogeneous modeling strategy, masonry units and mortar are distinctly described using continuum or discontinuous elements, blocks, joints and/or interfaces. Although the heterogeneous modeling allows a better description of the masonry behavior, the need of modeling separately bricks and mortar limits its applicability to small panels, while continuous modeling may be easily applied to large portions of masonry structures. A parametric analysis has been carried out on simple wall panels in order to evaluate the reliability of the two approaches and their capability to take into account some parameters that influence the structural behavior of masonry, such as the quality of constituent materials, the arrangement of bricks, the presence of openings. In this paper some of the results obtained are reported in order to provide a comparison between the two numerical approaches.