Traditional and Modern Techniques for Strengthening RC Columns under Seismic Loads: A Review

Abstract

Reinforced concrete (RC) columns are fundamental elements in structural systems. Vertical loads are transferred from the top of the structure to the foundation. Due to exposure to various environmental and structural factors such as bearing capacity, seismicity, and corrosion of rebars, columns are susceptible to performance degradation or loss of load-bearing capacity. Therefore, the application of strengthening techniques has become crucial for restoring column efficiency and improving their structural behavior. Recent years have witnessed significant advancements in strengthening methods, including the use of advanced composite materials such as fiber-reinforced polymer (FRP), in addition to ferrocement and other strengthening techniques. These modern methods offer an attractive alternative to traditional methods involving concrete and steel jackets. All these techniques increase the column's resistance to compressive, shear, and buckling forces, and also aim to improve the ductility and stiffness of the element as a whole. Environmental conditions, the nature of the damage, design requirements, feasibility of implementation, and cost are important factors in selecting the appropriate techniques. This review aims to study traditional and modern techniques used in RC columns, analyze the operating principle of each technique, and examine the factors affecting its effectiveness. Its performance and usage limits provide a knowledge base that contributes to improving design and engineering decisions in this vital field.