Retrofitting of Reinforced Concrete Beam with Externally Bonded CFRP

In our country many of the existing reinforced concrete structures are in need of repair or reconstruction, rehabilitation, because of deterioration due to various factors like corrosion, lack of detailing, failure of bonding between beam-column joints, increase in service loads, improper design and unexpected external lateral loads such as wind or seismic forces acting on a structure, environment and accident events etc., leading to cracking, spalling, loss of strength, deflection, etc. Strengthening of existing reinforced concrete structures is necessary to obtain an expected life span and achieve specific requirements. The need for efficient rehabilitation and strengthening techniques of existing concrete structures has resulted in research and development of composite strengthening systems. Recent experimental and analytical research have demonstrated that the use of composite materials for retrofitting existing structural components is more cost-effective and requires less effort and time than the traditional means. Fiber Reinforced Polymer (FRP) composite has been accepted in the construction industry as a capable substitute for repairing and strengthening of RCC structures. The superior properties of (FRP) polymer composite materials like high corrosion resistance, high strength, high stiffness, excellent fatigue performance and good resistance to chemical attack etc., has motivated the researchers and practicing engineers to use the polymer composites in the field of rehabilitation of structures. During past two decades, much research has been carried out on shear and flexural strengthening of reinforced concrete beams using different types of fiber reinforced polymers and adhesives. A detailed Literature review based on the previous experimental and analytical research on retrofitting of reinforced concrete beams is presented. Proposed method of strengthening the RC beam is decided based on the previous experimental and analytical research. Behaviors of retrofitted reinforced concrete beams with externally bonded CFRP with various types of resins (Epoxy, Orthophthalic Resin (GP), ISO resin) after initial load (60 % control beam) is investigated. Static load responses of all the beams under two point load method had evaluated in terms of flexural strength, crack observation, compositeness between CFRP fabric and concrete, and the associated failure modes.