Abstract
An experimental study was conducted to investigate the flexural behaviour of the pre-damaged reinforced concrete (RC) beams strengthened with carbon fiber reinforced polymer (CFRP). 25 beams with the size of 2200mm×150mm×200mm (length, width and height) were tested to bending loads. The parameters of the investigation included two pre-damage levels of RC beam, four shear span-depth ratios and two CFRP thicknesses. The effects of these parameters were analyzed on the failure modes, load carrying capacity, flexural stiffness and midspan CFRP strain of the strengthened beams. The results show that CFRP can significantly improve the flexural load carrying capacity of load-damaged RC beams. The pre-damage level has no obvious effects on the flexural behaviour of the strengthened RC beams with CFRP. With the decrease of the shear span-depth ratio, the failure mode of the strengthened beams may transform from debonding induced by intermediate crack (IC) to cover separation near CFRP end. For the strengthened beams failed by IC debonding, more CFRP can provide the higher load carrying capacity and flexural stiffness, but it is not the case for the beams failed by cover separation near CFRP end. Keywords: Carbon Fiber reinforced polymer (CFRP), StrengtheningÿPre-damage, Reinforced Concrete (RC), Shear span-depth ratio, Debonding