Failure mode-based calculation method for uniaxial compressive bearing capacities of corroded rectangular RC columns considering degradations of stirrup confinement effects

This paper introduced a failure mode-based calculation method for bearing capacities of corroded confined rectangular RC columns under uniaxial compressive loads, which specifically quantified the effects of stirrup corrosion on the deterioration of confinements on the core concrete. Through analyzing the stress states of corroded stirrups at failure of corroded RC columns under uniaxial compressive loads, three balanced failures and four failure modes were identified. Corresponding to three balanced failures, balanced corrosion degrees were defined and methods to calculate them were specified. Based on the corrosion degree and three balanced corrosion degrees of stirrups, four failure modes were identified and methods to calculate uniaxial compressive bearing capacities under different failure modes were specified. Subsequently, a dataset of uniaxial compressive tests on 69 corroded and 20 non-corroded control RC columns was collected from the literature. The predicted uniaxial compressive bearing capacities of corroded RC columns by the proposed failure mode-based calculation method were found in acceptable agreement with the test results, which demonstrated the validity of the proposed method. Finally, parametric studies were conducted and it was found that the developments of failure modes and uniaxial compressive bearing capacities with corrosion propagation differed noticeably from one another among RC columns with different initial details of cross-sections. The failure mode-based calculation method enables to predict failure mode first and calculate the uniaxial compressive bearing capacity later, which will contribute to safety assessments of existing corroded RC structures.