A RAPID REPAIR AND RETROFITTING INTERVENTION FOR SEISMIC DAMAGED CHINESE BRIDGE USING FIBER REINFORCED CONCRETE SHAPED REBAR AND EXTERNAL CFRP OR STEEL WRAPPING

A rapid repair and retrofitting technique applied on reinforced concrete (rc) bridges damaged after a strong earthquake, can be a very effective solution to guarantee the use of the bridge for the emergency response in short time. This repair intervention makes possible a proper plastic dissipation distribution on the rebars in plastic hinge only and increases the original insufficient shear strength minimizing the intervention time and cost. In this paper, the technique was applied on the most damaged pier of an irregular rc bridge designed according to Chinese codes (JTG D60-2004, JTG D62-2004 and JTG/T B02-012008) but with insufficient transversal steel reinforcement. The rc pier repair operations consist in: substitution of the original damaged rebar parts by shaped rebar; restoration of the damaged concrete parts by concrete with fibers in plastic hinge only. In particular, this research focuses on the use of fiber concrete to increase the insufficient original shear strength and ductility of the pier. Compression and flexural tests on fiber concrete specimens were performed to determine the variation of the concrete mechanical properties with different fiber contents. Furthermore, the shear strength of the repaired pier specimen was evaluated by CNR-DT 204/2006 formulations considering the contribution of the new and of the original concrete parts. Finally, some pier specimens (scale 1: 6) were repaired using different concrete mixture with different fiber contents to prove the feasibility of the intervention in situ.