Hybrid Finite Element for Masonry Arches and Axial-Symmetric Domes
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Historical architectural heritage includes a vast number of masonry structures characterized by curved elements whose structural behavior is strongly governed by geometry. The numerical modeling of curved masonry members with arbitrary geometry and no-tension material behavior represents a particularly challenging problem in computational structural mechanics. The intrinsic nonlinearity induced by the unilateral constitutive response, combined with geometric complexity, makes the structural response difficult to capture within standard numerical frameworks. While limit analysis and discrete element methods effectively capture collapse mechanisms, they may lack accuracy under service conditions or require high computational effort and extensive calibration. Classical displacement-based finite element methods, though widely used, can suffer from locking effects and poor stress prediction in curved masonry members, whereas force-based formulations, despite improved equilibrium representation, may result more involved, especially when applied to nonlinear or geometrically complex configurations. This study presents a curved mixed hybrid finite element specifically developed for the analysis of masonry arches of arbitrary shape. Furthermore, the element is improved for modeling axial-symmetric masonry domes. For this case, taking into account the modeling approach suggested in [2], where the analysis of the dome is recasted as a study of the generatrix considering also the effects along the parallel direction, the hybrid mixed finite element is modified and validated. The formulation is based on a two-field Hellinger–Reissner variational principle, with independent field of stresses, interpolated on the element domain, and displacements, computed at the element boundaries, enabling accurate force prediction and improved numerical robustness. Moreover, in the case of the arch-finite element, the equivalence of the approach with the force-based approach is also demonstrated. The element incorporates a Masonry-like Elastic No-Tension constitutive model, suitable for historical masonry characterized by negligible tensile strength. Moreover, a salient feature of the proposed element, both for the arch and dome modeling is its capacity to depict curved geometries of diverse shapes. The theoretical framework and numerical implementation are presented and discussed. Numerical applications demonstrate the accuracy, flexibility and computational efficiency.
