The Combined Retrofitting of Reinforced Light Structural Concrete Beams in Near Joint by Using of Steel Plates and CFRP Jacket under Cycling Loads

From the vulnerable part of reinforced concrete in bending frames resistant to earthquake, the near column area. In the beams retrofitting realm, the reinforcement of this area due to high shear forces enjoys an extreme importance. Among the main retrofitting methods, two methods are retrofitting by steel covers and CFRP Polymer coating which has their own special merits and demerits. In order to enjoy the merits and overcome the demerits, these to methods can be combined together. In this laboratory research, first 4 samples built with light reinforced concrete were destroyed under cycling loading. Then, 2 samples of concrete beams close to the joint area were made resistant by the concurrent using of steel plates and CFRP jackets and for the other two samples just CFRP was used. The steel plates were used for bending resistance and CFRP was used for making confinement and shear reinforcement. The results revealed good performance of these combined method in reinforcement of light structural concrete beams in the area close to the joint. That is, the coefficient index of reconstructed beams forming by combination compared with the use of CFRP only, was increased almost a hundred percent. Also, the sudden collapse of resistance during the loading was not registered in these samples.