Abstract：To investigate the bearing capacity and bending performance of box-type concrete beam strengthened with CFRP, the experiments of 8 reinforced concrete beams with different concrete strength, reinforcement ratio, CFRP amount and U hoop spacing were conducted. The results show that the bending performance of beam can be effectively improved by CFRP with increased yield load and ultimate load, and the strength properties can be fully played with good reinforcing effect. Because reinforcement of CFRP belongs to passive strengthening, the thin material has slight effect in the initial stage of loading with little impact on the crack load. The strengthening method has little influence on the stiffness before beam yield, while the rigidity is improved after yield. When the compression zone height x of standard beam is less than 2a′s, the special section of box-type beam does not need to be considered because the concrete does not participate in the calculation. The code for design of concrete structure on the beam of rectangular cross section formula specification can be used for the design with high accuracy. Specification of JTG J22—2008T calculation formula can be referred when the compression zone height x of strengthened beam with CFRP is less than 2a′s, but the accuracy is not high. The corrected reduction coefficient can improve the accuracy of results.
2015, Vol. 36 
