Flexural behaviour of C-FRCM strengthened corroded RC continuous beams

Abstract

This paper presents an experimental investigation on the flexural behaviour of corroded reinforced concrete (RC) continuous beams strengthened by carbon fabric-reinforced cementitious matrix (C-FRCM). A total of ten specimens with different degrees of corrosion were tested under in-plane bending. The strengthening C-FRCM plates were prefabricated with different layers of carbon fabric meshes for reinforcement, while some specimens were further strengthened by U-shaped wrapping for C-FRCM plates as the end anchorage. The flexural behaviour including failure modes, load-carrying capacities, deflections and redistribution of bending moment were carefully studied. The test results show that the load-carrying capacities of RC continuous beams were enhanced by the prefabricated C-FRCM plates and the enhancement further increased with the increase of the layer of carbon fabric meshes, in particular the specimens strengthened by U-shaped wrapping that effectively inhibited the debonding of C-FRCM plates. However, the redistribution capacities of the bending moment of RC continuous beams were weakened by the prefabricated C-FRCM plates. The design flexural strengths calculated using the design formulae given in ACI 440.2R-08, ACI 549.4R-13, AC434-0616-R1, FIB Bulletin 14 and CECS 146-2003 (2007) are also compared with the test flexural strengths, in which ACI 549.4R-13 and AC434-0616-R1 are the identical design guidelines for FRCM system, while the other three design guidelines are specific to FRP system. It is shown that the current design guidelines are all conservative for C-FRCM strengthened RC continuous beams, especially the specimens further strengthened by U-shaped wrapping, in which FIB Bulletin 14 provides the best predictions with the smallest value of COV.