Shear strengthening of RC beams with externally bonded CFRP sheets

The technique of strengthening or repairing reinforced concrete (RC) struct ures with externally bonded steel plates or composite sheets has been succe ssfully applied in civil engineering. The RC structure is often strengthene d in flexure. This work studies the effect of the shear strengthening of RC beams on the stress distribution, initial cracks, crack propagation, and u ltimate strength. Five types of beams with different strengthening carbon-f iber-reinforced plastic sheets are used. The experimental results show that it is not necessary to strengthen the entire concrete beam surface. The ge neral and regional behaviors of concrete beams with bonded carbon-fiber-rei nforced plastic sheets are studied with the help of strain gauges. The appe arance of the first cracks and the crack propagation in the structure up to the failure is monitored and discussed for five different strengthened bea ms. In particular, for one of the strengthened RC beams, the failure mode a nd the failure mechanism are fully analyzed.