Numerical and Experimental Validation of a 3D Macro-Model for the In-Plane and Out-Of-Plane Behavior of Unreinforced Masonry Walls

The behavior of historical UnReinforced Masonry (URM) buildings subjected to earthquake loading is usually governed by a complex interaction between the in-plane and out-of-plane response of masonry walls. In modern masonry building, the in-plane behavior of masonry walls is generally guaranteed in the structural design, but thin non-structural masonry infills are often vulnerable to out-of-plane actions. A reliable prediction of the combined in-plane and out-of-plane behavior of URM walls requires rigorous nonlinear finite element models, whose complexity and computational cost are generally unsuitable for current engineering applications, motivating the research of alternative numerical approaches. This article presents a study for validation of a 3D macro-model intended to simulate the combined in-plane and out-of-plane behavior of unreinforced masonry walls, against experimental results available in the literature and FEM simulations. The model is based on a three-dimensional macro-element whose kinematics is governed by seven degrees of freedom only. The mechanical behavior of the element is based on a fiber discretization approach that adopts basic material parameters. The performance of the proposed macro-element strategy is assessed by means of nonlinear static analyses performed on masonry walls, for which both numerical and experimental results are available in the literature.