Hysteresis Behavior of Reinforced Concrete Column Retrofitted and Repaired with Carbon Fiber Sheet

Abstract Structures experience damage and deterioration over their life cycle. The recent increase in interest in sustainable development of cities is re-evaluating the long-term use of structures. Therefore, researches on the retrofitting method for existing structures is receiving high attention again. However, there are very few cases where the direct comparison between the repair and retrofitting effects of structures has been experimentally verified. In this study, retrofitting methods and repair methods with carbon fiber sheets for reinforced concrete columns under shear failure were investigated. 10 reinforced concrete columns were tested under reversed cyclic loading. As a result of the experiment, it was found that, when reinforced with CFS strips, the increase in the width of the strip serves to enhance the strength and ductility of the reinforced member by providing confinement against shear cracks occurring in concrete. It was confirmed that as the number of overlaps of CFS increased, a greater strength-enhancing effect and ductility-enhancing effect appeared. However, the two-way reinforcement of CFS did not show a great effect in improving strength and ductility. As a result of evaluating the repair performance of damaged members using CFS, it was found that the strength and ductility of the repaired specimen exceeded the original strength and ductility of the base material as well as the strength and ductility of the reinforced specimen.