FEM Analysis of the Effect of Geometrical Radius on the Force Capacity of Unreinforced Masonry walls under Out-Of-Plane Monotonic Loading

The susceptibility of unreinforced masonry (URM) walls to out-of-plane (OOP) failure under lateral forces from earthquakes and high winds continues to be a critical concern in ensuring structural resilience and occupant safety. While curved wall construction has gained increasing global adoption for its architectural, functional, and spatial advantages, current design provisions are predominantly formulated for straight and orthogonal geometries, leaving the flexural performance of curved URM walls analytically underrepresented. This study conducts a numerical investigation into the geometrical curvature effect on the force capacity of URM walls using a three-dimensional brick-to-brick finite element approach in ABAQUS/CAE, implemented through the Simplified Micro-Modelling technique. The methodology involved a three-step process: first, a monotonic quasi-static simulation of a full-scale straight wall was performed to calibrate and validate the model; second, the validated model was extended to curved walls with varying projection radii; and third, the resulting force–displacement responses were analyzed to assess structural performance. The results show that curvature substantially improves OOP response, with yield pressure increasing from 3.0 kPa for the straight wall to 7.4kPa for the 1000mm projection wall (approximately 150% gain), while yield displacement reduced from 9mm to 2.2mm (approximately 75% reduction), indicating enhanced stiffness. Furthermore, curved walls exhibited superior ductility, energy absorption, and stable post-yield behavior due to geometric stiffening and the development of in-plane compressive membrane stresses, which delayed crack propagation and improved load-bearing capacity. These findings provide a validated predictive framework for understanding the structural performance of curved URM walls, highlighting curvature as an effective means of enhancing structural efficiency, resilience, and toughness in masonry design, with direct implications for developing performance-based seismic codes, guiding innovative architectural forms, and optimizing the use of locally available materials in sustainable construction. Keywords: Curved Masonry walls, Finite Element Modelling, Out-Of-Plane loads