Failure mode-based calculation method for bending bearing capacities of corroded RC beams strengthened with CFRP sheets

•Four balanced failures defined for CFRP sheet-strengthened corroded RC beams.•Five bending failure modes defined for CFRP sheet-strengthened corroded RC beams.•Failure mode-based calculation method for bending bearing capacities proposed. This paper proposed a failure mode-based calculation method for bending bearing capacities of CFRP sheet-strengthened corroded RC beams. According to the stress states of concrete, corroded steel bars and CFRP sheets at bending failure of the beam, four balanced failures and five failure modes were defined and identified. Both strengthening ratio-based approach and corrosion degree-based approach were proposed to identify failure modes. Then, the simplified calculation method was proposed for the bending bearing capacity of a CFRP sheet-strengthened corroded RC beam under each failure mode. Subsequently, a dataset with bending tests on 96 CFRP sheet-strengthened corroded RC beams and 122 CFRP-sheet strengthened non-corroded RC beams was established. The calculated bending bearing capacities were found in good agreement with experimental ones in the dataset, which demonstrated the validity of the proposed calculation method. The proposed failure mode-based calculation method enables to design strengthening ratios of CFRP sheets to achieve anticipated bending bearing capacities and bending failure modes for existing corroded RC beams (through strengthening ratio-based approach) and to assess the bending failure modes and bending bearing capacities of existing CFRP sheet-strengthened corroded RC beams (through corrosion degree-based approach), which will broaden the use of CFRP sheets in strengthening of corroded RC structures.