Retrofitting of Reinforced Concrete Beam with BFRP Sheets

The load-bearing capacity of RC structures decreases after years of service because of the cracking of concrete and the corrosion of reinforcing bar. In this chapter, investigations on the fundamental natural frequency of deteriorated RC box beam with initial flexural cracks and performance of deteriorated RC box beams retrofitted with BFRP sheets by three types of anchorage, such as U-strips anchorage, end anchorage with grooving, and steel plate anchorage, were conducted. Results showed that: (1) the load-bearing capacity and stiffness of the retrofitted RC box beam increased compared with those of the RC box beam without retrofitting; (2) end anchorage with grooving and steel plates anchorage increased the load-bearing capacity and stiffness, confined crack development of concrete, postponed the occurrence of BFRP debonding, and decreased the crack spacing compared with those of anchorage of FRP U-strips; and (3) the model for the natural frequency of the deteriorated RC box beam was proposed in consideration of depths and locations of cracks.