Effect of shear wall opening and reinforcement around opening on the structural strengthening

A common method for strengthening structures with low lateral stiffness is to add cast-in-place shear walls within a reinforced concrete (RC) frame. However, shear wall openings may be unavoidable in strengthening works due to architectural and installation requirements. In this study, the effect of the shear wall on structural strengthening was investigated by considering the cases with and without openings. A total of four inadequate RC frames (1/3 scale, single-story, single-span), reflecting common deficiencies observed in earthquake-damaged structures, were produced as part of the study. One of these frames was selected as a reference specimen and was not strengthened, while the others were strengthened with RC shear walls with and without openings. In one of the shear walls with an opening, special reinforcement details around the opening specified in the Turkish Building Earthquake Code (TBEC-2018) were applied and the effects of these reinforcements on the structural behavior were investigated. All specimens were tested under repeated and reversible loads simulating an earthquake. The experimental results were evaluated in terms of structural behavior parameters. The shear wall without opening increased the lateral load capacity by approximately 40% compared to the unstrengthened specimen. The application of TBEC-2018-compliant reinforcement around the opening improved the capacity by 16% relative to the unreinforced opening case. Initial stiffness increased by 35.3% with the use of opening reinforcement. Specimens without openings dissipated more energy in the plastic region, while opening reinforcement contributed positively up to peak load. Ductility decreased with the presence of openings, but improved with reinforcement.