Behaviour of Masonry Walls Under Combined Compression and Shear Loading: 3D Failure Analysis

This study investigates the nonlinear behaviour and failure mechanisms of masonry infill walls subjected to combined axial compression and lateral shear loading. Using the Drucker-Prager plasticity model within ANSYS Workbench, a 3D finite element model of a reinforced concrete (RC) frame with masonry infill was developed. The simulation focused on crack initiation, propagation, and ultimate load-bearing capacity. Results revealed initial stiffness due to confinement, followed by diagonal shear cracking as the dominant failure mode. The finite element analysis showed good agreement with analytical estimations, with a deviation of only ±6% in peak shear capacity. Contour plots of equivalent plastic strain and stress trajectories highlighted the development of tension-induced cracks and residual strength, emphasizing the role of RC confinement. The study validates the Drucker-Prager model for simulating pressure-sensitive masonry behaviour and offers insights into stress redistribution and damage evolution under complex loading. These findings contribute to performance-based design, retrofitting strategies, and structural assessments of masonry-infilled frames under seismic or lateral forces. Future work may incorporate cyclic or probabilistic modelling for enhanced accuracy in real-world applications.