PSI - Issue 70

Chaitra Shree V. et al. / Procedia Structural Integrity 70 (2025) 67–73

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loading conditions — particularly combined compression and shear — remains a subject of ongoing research due to the inherent nonlinearity and anisotropic properties of masonry assemblies. Understanding the failure mechanisms of masonry walls under these combined actions is critical for accurate structural assessment, retrofitting, and seismic design. In many practical scenarios, masonry walls are subjected to combined in-plane shear and compressive stresses, especially during seismic events or lateral loading induced by wind or ground movement. Under such loading, failure modes such as sliding, diagonal cracking, toe crushing, and rocking can occur depending on the aspect ratio of the wall, boundary conditions, and the interaction between the units and mortar joints (A. Page.2003; G. Milani 2007; L . Pela, X et al.2011) Recent advancements in computational modelling have enabled more detailed 3D simulations of masonry behavior under complex load paths. Finite element methods (FEM), discrete element methods (DEM), and micro-modelling techniques have been employed to capture the nonlinear and fracture-dominated response of masonry walls (T Lourenco,2002; M. Rots.1988; P.B Lourenco 1966; Sekkaki .M et.al 2024; Lourenco et.al) However, challenges persist in predicting the progressive damage evolution and capturing out-of-plane displacements that often accompany in-plane shear failures. Experimental studies have demonstrated that the failure mechanisms under combined compression and shear differ significantly from those under pure shear or pure compression (Laefer et.al 2008). The interaction between normal stresses and shear deformations leads to complex crack patterns, redistribution of stresses, and localized crushing, especially near supports and loading points. This necessitates a three-dimensional understanding of the failure process to develop reliable performance-based design criteria. Moreover, the anisotropic and heterogeneous nature of masonry, composed of bricks or blocks and mortar joints, introduces additional complexity. Mortar joint thickness, bond quality, and unit arrangement significantly influence the stiffness and strength under multi-axial loading conditions (Anthoine et al 1994; Van Zijl et al. 2004; Milani, G et.al 2012; Gabor et al. 2009; Magine et.al. 1997). This study presents a comprehensive 3D failure analysis of masonry walls under combined compression and shear, focusing on the interaction of material nonlinearity, crack propagation, and stress redistribution. Through detailed numerical modelling, the work aims to provide insights into failure mechanisms, critical stress zones of masonry structures. 2. Materials and Methodology This study investigates the nonlinear behavior and failure patterns of infill masonry walls subjected to combined axial compression and lateral shear loading. A single-bay reinforced concrete (RC) frame with a centrally placed masonry infill wall was modeled using ANSYS Workbench to simulate realistic structural boundary conditions. The wall measured 3.0 meters in width, 2.5 meters in height, and 0.25 meters in thickness, while the RC frame was composed of columns and beams with cross-sectional dimensions of 0.3 meters × 0.3 meters. The masonry infill was assigned material properties based on experimental data from literature and modeled using the Drucker-Prager (DP) plasticity criterion to represent the pressure-dependent yielding behavior of quasi-brittle materials. The material parameters considered for study is given in table 1.

Table 1. Material parameters considered for study Concrete (RC Frame)

Property E (MPa) ν fc'

Value 30000 0.2 30 MPa

Masonry Infill (Drucker-Prager Plasticity)

E (MPa) ν Cohesion, c Friction angle, ϕ Dilation angle Tensile strength Density

3000 0.2 0.2 MPa

30° 10° 0.15 MPa 2000 kg/m³