In the recent construction industry, Fiber reinforced polymers (FRPs) have been considered to be an innovative material to repair and strengthen damaged structures. It is because FRPs have many beneficial characteristics, such as corrosion resistance, a high tensile strength-to-weight ratio, non-conductivity and design flexibility. As a demand of FRPs has increased, many researches on behavior of the structures which were externally strengthened with FRPs have been conducted. However, researches on time-dependant behavior of the structures have not been conducted yet. In order to provide improved serviceability to reinforced concrete (RC) members, the behavior of the RC members strengthened with FRPs under sustained loads should be investigated. This paper presents a series of long-term experiments and deformation-recovery experiments. For the long-term experiments, three RC beams were fabricated and two of the beams were strengthened with a carbon fiber reinforced polymer (CFRP) plate and a glass fiber reinforced polymer (GFRP) plate respectively. The beams were placed under sustained loads for about 550 days. After the 550 days, all of the beams were unloaded for the measurement of deformation recovery. The deflection and strains of rebar and FRP reinforcements were measures for about 60 days. As the result of long-terms experiment, the beams strengthened with CFRP plate showed a better performance in terms of deflection and strains of rebar and CFRP plate. Moreover, the beam with CFRP plate showed a higher deformation recovery and residual strength than the other beams.
ANALYTICAL AND EXPERIMENTAL STUDY ON REPAIR EFFECTIVENESS OF CFRP SHEETS FOR RC BEAMS
