Experimental Assessment of the System-Level Seismic Performance of an Asymmetrical Reinforced Concrete Block–Wall Building with Boundary Elements

Using boundary elements in reinforced masonry (RM) walls allows closed ties to be used and multiple layers of vertical bars to be accommodated, thus providing a confining reinforcement cage. This enhances the overall performance of the RM wall relative to conventional RM wall with rectangular cross sections, which typically have a single-leg horizontal reinforcement and a single layer of vertical reinforcement. In addition, with the expected shift of design code developers’ focus from the component-level to the system-level assessment of seismic force resisting systems (SFRS), there is a need to experimentally quantify the system-level performance of RM buildings. To address this, an experimental asymmetrical two-story reduced-scale RM shear wall building with boundary elements, referred to as “Building IV,” was tested to failure under reversed cyclic loading that simulates seismic demands. Building IV was designed to have the same lateral resistance as a previously tested RM shear wall building with conventional rectangular configuration (without boundary elements), referred to as “Building III,” to allow for direct comparison. Therefore, after a brief summary of the experimental program, the focus of this paper is to compare the damage sequence and the load-displacement hysteretic behavior between the two buildings. The results show that higher levels of ductility accompanied by relatively smaller strength degradation were achieved during the test of Building IV compared to that of Building III. This study enlarges the database of system-level experimental results in an effort to facilitate the adoption of RM shear walls with boundary elements as a SFRS category within the next editions of the American and the Canadian masonry design standards.