Assessment of Safety of a Retrofitted Damaged Reinforced Concrete Column Based on the Bond Stress and the Stress Transfer at the Interface of the Reinforced Concrete Jacket and the Old Concrete

Abstract

Reinforced concrete columns in buildings undergo damage due to earthquakes, under-designed or erroneous designs, exposure to high temperatures, or due to overloading. Damaged reinforced concrete columns affect the safety and stability of the overall building. Hence, damaged reinforced columns are retrofitted to restore them, from strength and stability aspects, to improve their load-carrying capacity. In this study, retrofitting of an existing damaged reinforced concrete column of a commercial building has been carried out. The bond stress developed at the interface of the reinforced concrete jacket and the old concrete corresponding to the damaged reinforced concrete column is assessed by carrying out a three-dimensional finite element analysis. Based on the magnitude of the developed bond stress, the number of shear connectors to be provided to anchor the old and new concrete in the reinforced concrete jacket is decided. The shear and axial stresses developed in the shear connectors are also checked with the corresponding permissible material strength values. The safety of the retrofitted reinforced concrete column is assessed based on the bond stress values; the shear and axial stress developed in the shear connectors; and the number of shear connectors provided at the interface of the damaged reinforced concrete column and the reinforced concrete jacket.