Experimental and numerical investigations on the seismic behaviour of flexure-dominated reinforced concrete masonry shear walls with embedded boundary elements

Reinforced masonry shear walls (RMSWs) are widely used as seismic force resisting systems in low- and mid-rise buildings in Canada. They are typically designed to exhibit flexure-dominated behaviour, with nonlinear response concentrated at boundary regions that are often detailed as boundary elements (BEs). Previous research has primarily focused on extruded BEs formed using special block configurations to create barbell-shaped or flanged-shaped sections, which improve ductility. However, data remains limited for embedded BEs confined within the wall thickness. This dissertation presents experimental and analytical investigations on the seismic behaviour of RMSWs with embedded BEs. The embedded BEs were constructed using modified hollow concrete blocks, allowing concentrated vertical reinforcement and transverse ties. The experimental program included prism and full-size wall tests. A total of 25 prism specimens (5 unreinforced and 20 reinforced) were tested under uniaxial compression to examine the effects of tie configuration and spacing. Four full-size RMSWs, including a control wall and walls with embedded BEs using different tie details, were designed and constructed. Three of them were tested under reversed cyclic loading while two of the tested walls are included in this dissertation. This study focuses on walls without BEs and with embedded BEs confined by 135-degree hooked ties. The tests quantified ductility, failure modes, and cyclic force-displacement behaviour. A mechanics-based macro-model was developed to simulate the in-plane cyclic response of RMSWs with and without embedded BEs. The model extends the Multiple Vertical Line Element Model (MVLEM) by incorporating a softened strut-and-tie approach to capture interactions between shear and flexural behaviour, including strength degradation due to diagonal cracking. An empirical model was also proposed to predict the ultimate drift capacity of flexure-dominated RMSWs based on an experimental database. The results show that transverse reinforcement significantly enhances the compressive strength and ductility of embedded BEs. This study provides the first full-size experimental evidence of RMSWs with embedded BEs. The proposed macro-model offers an efficient tool for simulating cyclic behaviour, and the empirical drift model enables improved definition of drift-based limit states. Together, these contributions support more reliable performance assessment and design of RMSW systems.