Experimental investigation on the seismic retrofitting of non-confined reinforced concrete shear walls by forming boundary elements using carbon fiber polymer ropes

It is an indisputable fact that Turkey is located in a tectonically active region, which makes it highly vulnerable to some of the world's most destructive earthquakes. As a result, national seismic codes are regularly revised and improved in light of advances in engineering and technology. This ongoing risk highlights the urgent need to enhance the seismic performance of the existing building stock. Numerous researchers continue to contribute to this effort by developing and evaluating retrofitting methods for deficient structures. In 1998, a significant regulation was introduced in Turkey that mandated the inclusion of boundary elements in reinforced concrete shear walls. However, many structures constructed prior to this regulation lack such elements and therefore require seismic retrofitting to improve their resistance to earthquake-induced forces. Recent studies have demonstrated that the application of carbon fiber reinforcement to the boundary elements of shear walls significantly enhances their ductility. A novel retrofitting technique has been proposed, in which carbon fiber bundles are externally applied to the boundary elements of shear walls. Experimental observations indicate that the grooves opened in the boundary elements initially lead to a reduction in stiffness up to a story drift ratio of 0.008. Nevertheless, at higher drift levels, carbon fiber reinforcement contributes significantly to the structural stiffness, making this method a promising alternative for the seismic strengthening of existing structure elements.