Finite Element Study of Behavior of RC Bridge Beams Strengthened with CFRP

The experimental results show that using Carbon Fiber Reinforcement Polymer (CFRP) is an effective mean for strengthening RC beams. This study focuses mainly on the flexural performance of reinforced concrete bridge beams strengthened with two different (CFRP) systems: Externally Bonded Strips (EB) and Near Surface Method Strips (NSM), and evaluate the efficiency of this tow techniques in increasing the load carrying capacity of concrete beams subjected to bending due to monotonic loads. At first, the results from the FE models are compared with the ACI440 provisions and the experimental data for three beams with different conditions from researches that are in good agreement. Furthermore, the FE models were extended to simulate the behavior of full-scale bridge girders recovered from a 42-year old Interstate bridge and examined by Aidoo et al. The specimens had been retrofitted with EB and NSM techniques and subjected to monotonic loading to failure. The load deflection plots obtained from numerical study show good agreement with the experimental plots reported by Aidoo, et al. After that, the models were used to examine the influence of arrangement, number, amount of CFRP in EB technique and number of grooves, dimension of grooves, in NSM technique, on the strength and ductility of FRP strengthened beam. The effect of retrofitting on unloaded and preloaded beams was studied too. The results indicate that, increasing the percentage of CFRP increases the ultimate strength by 30%. But by changing the number of layers from 4 to 1 at the center toward the supports, the ultimate load increases 33.3% in comparison with reference beam, and the beams strengthened with NSM achieved higher ultimate load (10 per cent) than beams strengthened with EB. The level of preload, prior to the installation of CFRP, does not affect the overall behavior of the strengthened specimens.