SIMPLE INTERFACE ELEMENT EQUIPPED WITH THICKNESS FOR THE NON-LINEAR STATIC HETEROGENEOUS ANALYSIS OF MASONRY WALLS IN-PLANE LOADED: IMPLEMENTATION AND VALIDATION

This paper presents a novel interface model -within non-linear Finite Element heterogeneous computations- for discretizing mortar joints in masonry walls subjected to in-plane loads. The proposed interface model accounts for the actual thickness of the joints, and employs isoparametric four-node quadrilateral elements, ensuring that normal stress along the joint direction is vanishing, allowing for a phenomenological formulation of the non-linear mortar behavior, based on experimental data. Mechanical parameters for the joints are directly derived from standard tension, compression, and shear tests on mortar and masonry triplets, thus facilitating practical application in design. A progressive elastic stiffness relaxation algorithm is implemented to handle non-linearity and softening, making the FE code particularly efficient for practitioners. Additionally, bricks are modeled with elastic elements, with the potential for incorporating non-linearity through interfaces. The developed software, FEMANOLA v3.0 (Finite Element Masonry Non-Linear Analysis), features a user-friendly interface for mesh creation and application of loads and is validated against experimental data from a windowed panel subjected to static shear until failure. This approach aims to enhance the accuracy and efficiency of seismic assessments in masonry structures while remaining accessible for common design practices.