Performance and strength calculation of CFST columns with localized pitting corrosion damage

In recent years, concrete-filled steel tubular (CFST) columns are increasingly used in ocean construction, such as offshore towers and marine platforms. When used in harsh marine environments, the inevitable pitting corrosion poses a crucial threat to the outer surface of CFST and results in stress concentration, early local buckling as well as confinement reduction towards concrete. Relevant study is rarely seen given the complexity in experimental realization and numerical modelling of random pitting corrosion. This study aims to investigate the nonlinear performance of CFST columns with localized pitting corrosion damage. Advanced finite element modelling techniques are developed to simulate the localized corrosion pits with the consideration of its random nature in terms of sizes, depths and distributions. Previous test data are adopted to verify the developed model. The differences between the structural performance of CFST columns under pitting corrosion, uniform corrosion and uncorroded conditions are revealed. Comparison results demonstrate a more severe degradation caused by localized pitting corrosion. Finally, taking the characteristic of pitting corrosion into account, simplified design methods are proposed by modifying the existing methods in the current standards for calculating the postcorrosion strength of CFST columns.