Flexural FRP Strengthening of Concrete Bridges Using an Innovative Concept

This paper presents an innovative method for flexural strengthening of reinforced concrete (RC) bridges using pre-stressed carbon fiber reinforced polymer (CFRP) laminates as externally bonded reinforcement (EBR) and glass-fiber reinforced polymer (GFRP) deck panels. The work was a part of an EU-funded project called sustainable refurbishment of existing bridges (SUREBridge). The innovative features of this concept include the tensile reinforcement of the section using self-anchored pre-stressed CFRP laminates and compressive reinforcement of the section using tailor-made GFRP deck panels at the same time. The flexural behavior of RC T-section beams, strengthened using this concept, has been studied experimentally. Four 6-meter-long beams-three strengthened with bonded pre-stressed CFRP laminates in bottom with a pre-stressing force of 100 kN and GFRP deck panels on the top side and one as control beam-were tested in four-point bending configuration. The results indicated a substantial increase of ca. 160% in ultimate load carrying capacity of the strengthened beams as well as considerable improvements in flexural stiffness and cracking loads. The strengthened beams also displayed a ductile behavior after debonding of externally bonded CFRP laminates while maintaining the maximum load level before debonding due to the strong bond between the GFRP decks panels and the concrete beam. It was concluded that the proposed method has the potential to be introduced as a reliable method for strengthening of old concrete bridges.