Effect of C-FRP on Increasing the Bending Capacity of Reinforced Concrete Beams with Lower Compression Strength

FRP is used in different cases for retrofitting of concrete members, but the distinction of resistance level of concrete in order to be retrofitted with FRP, needs more research and investigation. In this study, observation on the behavior of reinforced concrete beams with lower level of strength, which are supported with C – FRP, has been carried out. For this purpose, 28 models of reinforced concrete beams, with 8 to 20 Mpa compression strength, were made in laboratory and 14 models were reinforced with one layer of C–FRP. Then, specimens were loaded under impression of bending by concentrated force at the middle of the span. From the results of this study, it is concluded that C-FRP makes no important effect on increasing the bending capacity of reinforced beams in models with low level of concrete strength, and it can happen due to delaminating of FRP layers from the surface of concrete and consequently concrete cracks. However, observations and results show that C-FRP is more appropriate for beams with concrete compression strength of 18 Mpa or more.