A numerical continuous micro-model based on the space angular decomposition (Multi-Laminate framework) to analyze three-dimensional nonlinear behavior in masonry

This research presents a novel three-dimensional continuous micro-model for analyzing unreinforced masonry structures. The model utilizes a multi-laminate concept to accurately capture the mechanical behavior and failure mechanisms of these structures. It provides offers significant advantages through its simplified parameter requirements, needing only cohesion (c) and friction angle (φ) as fundamental material properties, while maintaining robust predictive capabilities. By adopting a continuum-based approach, the formulation eliminates the complexity associated with discrete joint elements, thereby streamlining the entire computational process from mesh generation to results interpretation. The yield surface employed in this model includes the generalized 2D Mohr-Coulomb, along with tension and compression cut-offs. Through innovative spatial angular decomposition, this computationally efficient 2D formulation successfully represents complete three-dimensional material behavior, including confinement-dependent strength evolution, pressure-controlled dilatancy effects, and both inherent and stress-induced anisotropy. The proposed model is validated at both the specimen and structural levels. Predictions at the specimen level are obtained by integrating the incremental constitutive relations with a 3D test element. The Brazilian test on the masonry core, masonry panel under uniaxial and biaxial stress states, and masonry wall has been chosen to demonstrate the capabilities of this model. Experimental validation demonstrates the model's accuracy in predicting load-displacement responses and failure patterns when compared against laboratory measurements and established numerical benchmarks. The results confirm the model's reliability across different scales of analysis while maintaining computational efficiency. This balanced combination of theoretical rigor and practical applicability makes the proposed approach particularly valuable for engineering applications involving unreinforced masonry structures, offering researchers and practitioners an effective tool that requires minimal material characterization while delivering comprehensive behavioral predictions.