Detailed micro-modelling of unreinforced masonry walls: a parametric in-plane cyclic study

Unreinforced masonry walls (UMWs) exhibit insufficient seismic capacity owing to their low tensile strength, rapid stiffness degradation, and brittle failure under cyclic in-plane loading. This study proposed a detailed micro-modelling approach to simulate the in-plane behaviour of UMWs. The finite element model was initially validated against experimental data for load–displacement response, stiffness degradation, energy dissipation, ductility, and failure mode, indicating good agreement with observed behaviour. Following validation, a one-at-a-time parametric study was conducted to examine the relative effects of aspect ratio, masonry compressive strength, and wall thickness on the structural performance of UMWs. The results suggest that aspect ratio plays a significant role in determining deformation mode, energy dissipation, and ductility, with intermediate aspect ratios providing an effective compromise between strength and deformation capacity. Increasing masonry strength significantly improves shear resistance and initial stiffness; however, its effectiveness in improving ductility and post-peak behaviour remains limited. The wall thickness has a significant effect on the shear resistance and stiffness retention due to the increased cross-sectional area; however, excessive thickness may lead to reduced deformability. Overall, the findings highlight the fundamental limitations of UMWs under cyclic in-plane loading and underscore the importance of geometric characteristics in influencing seismic performance.