Citation: Rainone, L.S.; Tateo, V.; Casolo, S.; Uva, G. About the Use of Concrete Damage Plasticity for Modeling Masonry Post-Elastic Behavior. Buildings 2023, 13, 1915. https://doi.org/10.3390/ buildings13081915 Academic Editor: Mohamed K. Ismail Received: 1 July 2023 Revised: 16 July 2023 Accepted: 18 July 2023 Published: 27 July 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). buildings Article About the Use of Concrete Damage Plasticity for Modeling Masonry Post-Elastic Behavior Luigi Salvatore Rainone 1 , Vito Tateo 1 , Siro Casolo 2 and Giuseppina Uva 1, * 1 DICATECH Department, Politecnico di Bari, 70125 Bari, Italy; l.rainone@studenti.poliba.it (L.S.R.); vito.tateo@polimi.it (V.T.) 2 ABC Department, Politecnico di Milano, 20133 Milano, Italy; siro.casolo@polimi.it * Correspondence: giuseppina.uva@poliba.it; Tel.: +39-805963832 Abstract: Considering the high vulnerability of existing masonry buildings, which often have strategic or cultural value, professionals and specialized engineers are frequently required to model complex historical buildings. The approaches proposed by National Building Codes may not always be suitable for such cases, but more detailed approaches are necessary, relying on FEM continuum modeling and inelastic constitutive law. There are many constitutive laws proposed in the literature that allow us to accurately reproduce the mechanical behavior of masonry. However, they require the identification of several parameters that are not easy to determine. In this study, a sensitivity analysis of the parameters of a nonlinear constitutive law very popular for masonry modeling (the “Concrete Damage Plasticity—CDP” model) is conducted, considering literature tests of masonry panels under shear stress as the benchmark. The aim is to assess the influence of the main parameters of the model and compare them to one of the more commonly used Mohr–Coulomb failure criteria. Keywords: masonry; FEM; concrete damage plasticity; sensitivity analysis; dilatancy; post elastic behavior 1. Introduction The numerical modeling of masonry structures is a challenging issue because masonry is a composite material obtained by assembling blocks with or without an interposed layer of mortar. Blocks can be more or less regular, made of different materials such as stone, calcarenite, clay, or concrete, and assembled in one or more layers, according to regular patterns or chaotically. Around the world, there are different traditions, different materials available, and consequently, different masonry types [1,2]. Despite the diversity of masonry typologies, they all have some recurring peculiarities that have challenged researchers and technicians over the years. As a general feature, masonry can be classified as non-homogeneous, orthotropic, and brittle. These properties are related to the construction technology, i.e., the presence of a pattern of discrete blocks, that determines the material anisotropy. In general, for regular patterns, such as the running, the common, and the English or the Flemish bond, masonry walls have continuous horizontal joints and staggered vertical joints. This micro-structure, with the interposition of mortar layers, causes the masonry wall to respond differently depending on the direction of stress. Furthermore, since both mortar and blocks usually have a brittle response with limited tensile strength, the masonry also shows a brittle response. Moreover, an accurate model should also consider the large dispersion that characterizes the material strength, as reported by Gooch et al. [3]. In order to deal with these peculiarities, depending also on the scale of the analysis, different modeling strategies have been developed in the literature [4–9]. D’Altri et al. [10], and other authors in different applications [11], report a useful review that highlights the strengths and weaknesses of many different approaches. A major distinction is possible between micro models and homogeneous models. Different types of approaches belong Buildings 2023, 13, 1915. https://doi.org/10.3390/buildings13081915 https://www.mdpi.com/journal/buildings