Experimental Study on Flexural Strengthening of RC Columns with Near Surface Mounted FRP Bars

Document Type : Structural Earthquake Engineering


K.N. Toosi University of Technology


The effectiveness of FRP jackets for increasing the compression strength, shear strength and ductility of reinforced concrete (RC) columns was demonstrated in many studies, but the influence of FRP jacketing on the flexural capacity of columns is minimal. In this paper, a new retrofit method, which utilized near surface mounted (NSM) fiber reinforced polymer (FRP), was studied aiming to improve the flexural capacity of RC columns subjected to bending and compression. This technique is based on bonding fiber reinforced polymer (FRP) bars into grooves cut in the cover of RC columns. For this purpose, five reinforced concrete column specimens were designed, constructed and subjected to constant axial compression and lateral cyclic loading. In addition, the strengthened columns were wrapped with carbon composites to satisfy seismic detailing requirements. The test results show that by using the NSM technique, the flexural strength and lateral load capacity of the columns increase significantly. The test results were also compared with the results obtained from the analytical study that was conducted based on strain compatibility. A good agreement between analytical and experimental results was observed.