Assessing a Retrofitting Method for Existing RC Buildings with Low Seismic Capacity in Turkey

In this research, external retrofit of reinforced concrete (RC) buildings, especially the ones located in Turkey, was studied. Most of Turkey’s population live in an active seismic zone where frequent earthquakes are experienced. Turkey’s existing residential building stock consists mainly of reinforced concrete buildings that are prone to earthquake damage because of a lack of lateral strength. Therefore, a fast and feasible shear retrofit method for these buildings is crucial. In this study, three six-story prototype RC buildings were created to study the effectiveness of external shear retrofit with and without the inclusion of window openings, constructed at building corners. As always desired, this retrofit method was shown to be fast to apply and its construction requires minor damage on the building. The three-dimensional (3D) finite-element model of the building was analyzed nonlinearly by a commercially available software package. The modeling of concrete material as well as embedded steel reinforcement was proved to be satisfactory by calibrating them with three $1/3$-scaled RC frame retrofit experiments existing in the literature. The effect of corner shear walls with and without window openings on the base shear capacity and lateral stiffness was assessed comparing with the bare frame. The shear contributions of columns and shear walls for the model buildings were also compared. Considerable amount of capacity increase in base shear and stiffness was achieved by the addition of external shear walls, even with the inclusion of window openings.