Shear Strengthening by GFRPU on an RC Column with Nonseismic Reinforcement Details

Structures constructed before seismic design standards in Korea were enacted are being seismically and structurally strengthened for structural performance. The jacket method has been used to enhance the shear load-carrying capacity and ductility of reinforced concrete columns. This study investigated the effect of glass fiber-reinforced polyurea (GFRPU) on the enhancement of shear strength and ductility. It was shown that the GFRPU spraying technique played an important role in enhancing the column because of the material characteristics of the GFRPU, that is, high-tensile strength and elongation. The reinforcement effect of GFRPU on the shear-span ratio and axial-force ratio of six reinforced concrete (RC) column specimens was evaluated. The experimental results demonstrated that the lateral-reinforcement effect and energy-dissipation capacity were improved. The H-series and S-series specimens reinforced by the GFRPU with an axial-load ratio of 0.1 exhibited higher shear strength, of about 30% and 18%, than the specimens without reinforcement. The shear-load-carrying capacity of the S-series specimen with the axial-load-force ratio of 0.2 increased by 4%. The design method representing the lateral-resistance ability of the GFRPU was represented by an empirical formula reflecting the experimental results.