Behavior of Seismically Detailed Reinforced Concrete Block Shear Walls with Boundary Elements under Out-of-Plane Loading

Although boundary elements have been known to enhance the in-plane performance of reinforced concrete block shear walls under seismic loading, research examining their influence on the walls’ out-of-plane performance (e.g., due to blast loading) is very scarce. Unlike conventional walls with rectangular cross sections, boundary elements allow the use of closed ties and multiple layers of vertical reinforcement, thus enhancing the wall’s overall out-of-plane resistance and stiffness. Nevertheless, the corresponding wall performance and damage sequence beyond peak resistance have been neither experimentally nor analytically quantified to date. Therefore, current blast standards do not assign unique design requirements or response limits for reinforced concrete block walls with boundary elements due to the limited number of relevant studies published when these standards were originally developed. To address this knowledge gap, an experimental program was initiated to investigate the out-of-plane performance of seven scaled seismically-detailed reinforced concrete block axially loaded walls with boundary elements under quasi-static displacement-controlled cyclic loading. Several design parameters were considered in the test matrix, which included the wall vertical reinforcement ratio and distribution, the boundary elements alignment relative to the wall web, the wall aspect ratio, and axial load level. The resistance function of the walls and the corresponding damage sequence, as well as the ductility capacity were also used to assess the walls’ out-of-plane performances. Finally, two experimentally validated models, based on plastic analysis, were developed to generate the resistance functions of all walls. The experimental and analytical results in the current study demonstrated the importance of considering the two-way bending mechanism associated with reinforced concrete block walls with boundary elements when their performance is evaluated under out-of-plane loading demands.