Residual load-bearing capacity of corroded reinforced concrete columns with an annular cross-section

Reinforced concrete (RC) columns with an annular cross-section are commonly utilized as supporting structural members in ocean engineering structures, and their structural performance deterioration is mainly caused by the corrosion of rebar in aggressive marine environment. This paper proposes an effective method to investigate the effects of rebar corrosion on the structural performance of the annular RC columns under various loading conditions. Firstly, the material degradation and residual structural strength models are proposed based on the analysis of the corrosion-induced deterioration of RC structures. Then, the general method for determining the load-bearing capacity is developed using the equivalent steel ring assumption. To improve computational efficiency and practical applicability, an effective method for assessing the residual load-bearing capacity is proposed by simplifying the calculations of rebar load-bearing capacity coefficients using the regression fitting approach. Finally, the effectiveness of the proposed simplified method is demonstrated with the relevant experimental data available. The results show the capacity deterioration rate is strongly related to the corrosion level and loading condition with the most severe degradation typically at the corrosion level of 5-10%, and the smaller and larger eccentric columns drop the capacities by about 28% and 41% at 10% corrosion level, respectively.