Numerical parametric investigation on the compression and shear-compression response of masonry panels strengthened by CRM

In recent years, strengthening techniques based on externally bonded composite materials have been increasingly adopted to improve the structural performance of masonry structures. Among these, Composite Reinforced Mortar (CRM) systems have proven effective for both compression and shear-compression retrofitting. Despite their growing use in engineering practice, research on CRM-strengthened masonry remains limited, particularly about in-plane flexural capacity, drift performance, and the contribution of CRM layers to out-of-plane stability. Moreover, comprehensive analytical models capable of explicitly quantifying the mechanical contribution of CRM reinforcement are still lacking, with current design guidelines mainly relying on simplified amplification factors applied to masonry mechanical properties. This study presents the development of a finite-element model capable of reproducing both the shear-compression response and the out-of-plane buckling behavior of masonry walls under compression strengthened with CRM systems. A parametric numerical investigation is carried out to analyze the in-plane shear response and out-of-plane buckling behavior of CRM-retrofitted panels. The numerical models are calibrated using experimental results from previous tests conducted by the authors and validated against additional data available in the literature. The results identify the key parameters governing the CRM–masonry interaction and enable the proposal of an analytical approach for estimating the effective mechanical properties of retrofitted masonry panels.