Natalia Pingaro, Gabriele Milani
This paper presents a novel interface Finite Element for the discretization of mortar in masonry walls subjected to in-plane loads. The proposed interface model accounts for the actual thickness of the joints, employing isoparametric four-node quadrilateral elements where normal stress along the joint direction is enforced to zero. A phenomenological non-linear constitutive behavior based on experimental data is also proposed for mortar, a feature which enhances the model predictivity in non-linear heterogeneous computations. Mechanical parameters for the joints are directly derived from standard tension, compression, and shear tests performed on mortar and masonry triplets, thus facilitating practical applicability in common design. A progressive elastic stiffness relaxation algorithm is implemented to handle non-linearity and softening, making the FE code particularly fast and robust. Additionally, bricks are modeled with elastic elements, with the potential for incorporating bulk-brick non-linearity through interfaces. The developed software, FEMANOLA v3.0 (Finite Element MAsonry NOn-Linear Analysis), features a user-friendly interface for mesh creation, application of loads, and post-processing inquiries. Validation is carried out through three different examples, namely a masonry triplet subjected to shear, an in-situ tested arch, and a windowed shear panel. Excellent agreement with both experimental data and previous numerical results is obtained in all cases. • Novel interface element with thickness for heterogeneous FE nonlinear analysis of masonry walls. • Phenomenological constitutive law for mortar based on tension, compression, triplet shear tests. • Explicit algorithm to deal with softening and nonlinearity based on elastic modulus relaxation. • Efficient implementation with user-friendly interface. • Validation on diverse benchmark cases (triplet test, point loaded arch, and windowed shear panel).