Structural behavior of corroded RC beams with/without stirrups repaired with CFRP sheets

Abstract

Strengthening/repair of existing reinforced concrete structures has become one of the important issues in the field of civil engineering. In reinforced concrete structures located in hot and humid areas, steel reinforcement is generally vulnerable to deterioration due to corrosion. Corrosion of reinforcement in many cases is considered the main cause of concrete structures deterioration which in turn requires large budgets for repair and maintenance. This paper presents the experimental results of damaged/repaired reinforced concrete beams. The experimental program consisted of testing 12 reinforced concrete rectangular beam specimens with/without shear reinforcement and exposed to accelerated corrosion. The corrosion level was varied between 5 and 7.5 % which represents mass loss of the longitudinal steel reinforcement on the tension side. Corroded beams without shear reinforcement were repaired by bonding longitudinal carbon fiber reinforced polymer (CFRP) sheets to the tension side in addition to external U-shaped CFRP sheets to restore the strength loss due to corrosion. Corroded beams with stirrups were repaired by bonding longitudinal CFRP sheets to the tension side only. The test results showed that using externally bonded U-shaped CFRP sheets restored the ductility of corroded beams without stirrups and prevented bond failure at the steel concrete interface due to the absence of internal stirrups. In addition, combining U-shaped and longitudinal CFRP sheets enhanced the ultimate load by 37 % and the stiffness by 25 % in corroded beams without stirrups. For corroded beams with stirrups ductile failure was observed. Corroded beams with stirrups strengthened with CFRP sustained higher failure loads; however, the stiffness was unchanged.