Performance enhancement of reinforced concrete columns using stainless steel and galvanized steel plates: Experimental and numerical investigation

Abstract This study introduces an innovative approach to strengthening defected reinforced concrete (RC) columns using externally bonded stainless steel and galvanized steel plates. Unlike conventional strengthening methods, this technique replaces traditional transverse stirrups with steel sheets, providing enhanced confinement and ductility. The experimental program involved static load testing to collapse a series of RC columns, including a master column with adequate transverse reinforcement and defected columns with reduced stirrups to simulate structural weaknesses. The defected columns were strengthened using stainless steel and galvanized steel plates in arrangements to evaluate the influence of different plate configurations (three‐layer vs. four‐layer) and volume ratios (2% vs. 3%) on structural performance. Experimental results show that strengthening with a 3% ratio of stainless steel plates increased the ultimate load capacity by up to 66%, while galvanized steel plates achieved a 58% improvement. The ductility of strengthened columns improved compared to the defected columns. The energy absorption capacity increased significantly, with the four‐layer stainless steel configuration achieving a 370% enhancement over the unstrengthened specimen, with a slightly lower value for galvanized steel plates. In addition, a finite element model was developed to simulate the performance of the tested columns. The finite element modeling accurately captured the experimental failure modes and load–displacement behavior, validating the effectiveness of this strengthening approach. A parametric study was conducted to investigate further the relationship between sheet thickness and ultimate load‐bearing capacity. The study provides practical insights for optimizing plate configurations to balance structural performance and material efficiency, offering a cost‐effective solution for enhancing aging or under‐designed RC structures. These findings demonstrate that using stainless steel and galvanized steel plates is a viable alternative for strengthening RC columns, particularly for seismic retrofitting applications.