Reinforced masonry shear walls (RMSWs) are commonly used in seismic regions, but predicting their behaviour is challenging due to the composite nature of materials like masonry blocks, mortar, steel rebars, and grout. This complexity is heightened in partially grouted (PG) walls, where stiffness discontinuities occur at interfaces between grouted and ungrouted cells. The scarcity of experimental data on the materials’ properties has further complicated the development of accurate analytical models.
This research aims to enhance the lateral performance of PG masonry shear walls and develop a reliable analytical model. The study is divided into two main Phases: analytical and experimental. In the analytical phase (Phase I), a nonlinear finite element model was developed and validated against experimental data from the literature. Due to the lack of material properties in existing studies, assumptions were made to fill these gaps. The model generated a comprehensive matrix of 196 numerical models, covering a wide range of parameters such as aspect ratio, spacing between grouted cells, axial load, reinforcement ratios, and grouted and ungrouted compressive strengths. In the experimental phase (Phase II), 84 masonry prisms were tested to evaluate the compressive, shear, and tensile properties of grouted, ungrouted, and boundary element masonry assemblages. Consequently, using these components, two half-scale PG shear wall specimens with C-shaped boundary elements were constructed and tested under high axial loads and in-plane cyclic loading. These tests represented the lower storey of RMSWs in of a six- and twelve-storey buildings and examined the impact of full versus partial grouting and aspect ratios. 
The analytical investigation resulted in three penta-linear load-displacement backbone models for flexural-dominated, shear-dominated, and combined failure modes, along with secant stiffness expressions for each wall type. These models were validated against additional data, showing good accuracy for PG walls. The study also identified the inadequacy of the stiffness reduction factor in CSA S304-14 for PG walls, leading to the derivation of new coefficients. The experimental results provided detailed stress-strain data for various mechanical properties, and wall tests showed ductile performance with high energy dissipation, exceeding North American design standards before strength degradation began.