Effect of prestress and transverse grooves on reinforced concrete beams prestressed with near-surface-mounted carbon fiber-reinforced polymer plates

The effects of prestress levels on the flexural behavior of concrete beams strengthened with near-surface-mounted (NSM) fiber-reinforced polymers (FRPs) were experimentally evaluated. Eight beams were tested. Failure of the prestressed strengthened beams occurred because of concrete cover separations at one end of the carbon FRP (CFRP) plates. With increasing prestress levels, the cracking, yield, and ultimate loads of the beams increased. The effect on the deflection corresponding to the cracking and yield loads was not significant; however, the ultimate deflections were affected by prestressing. The recommended prestress level for the concrete beams was ≤50% of the CFRP rupture strength.