Flexural behavior of RC beams strengthened by NSM GFRP Bars having different end conditions

Near surface mounted (NSM) fiber reinforced polymer (FRP) bars became more effective in strengthening reinforced concrete (RC) beams. This is because it increases the bond capacity and makes a protection against external damage. Most of previous related researches stated that the failure of the tested RC strengthened beams with NSM FRP is due to debonding or concrete cover separation. In this research the ends of the NSM glass fiber reinforced polymer (GFRP) bars were bent to delay or prevent NSM FRP debonding and concrete cover separation and thus increasing the load carrying capacity of the strengthened beams. The inclination angles of GFRP bars with bent ends were 90° and 45°. Straight GFRP bars with variable lengths were also used for comparison. The test results demonstrated that the GFRP bars with bent ends prevented the concrete cover separation and increased the load carrying capacity of the strengthened beams. The load carrying capacity of the strengthened beams by straight NSM bars and those having 45° and 90° inclined ends were 177%, 201%, and 185% of that of their control beam, respectively.