Eccentric compression capacity of circular CFST columns under random pitting corrosion

This study explores how random pitting corrosion affects the ultimate eccentric load-carrying capacity of corroded CFST columns at various corrosion levels. The research examines how the load-carrying capacity of circular steel tube concrete columns changes under eccentric loading conditions due to variations in the quality loss rate of the external steel tube caused by corrosion. The established finite element model is validated using existing experimental data, showing a high degree of accuracy. Additionally, the study investigates influencing factors, including corrosion thickness (tc/t), both constant and random corrosion (tc/t), eccentricity (e), corrosion pit diameter (Dc), material strength, and component dimensions. The findings reveal how these parameters affect the reduction of eccentric compressive load-carrying capacity. To visually illustrate this effect, the concepts of load reduction factors R ' cs and R ' c are introduced, representing the ratio of load-carrying capacity before and after corrosion. Based on extensive random finite element analyses, we propose a load-carrying capacity calculation formula for the eccentric load reduction factor applicable to corroded circular CFST columns. The study also demonstrates that axial compression can be considered a special case of eccentric loading with an eccentricity of 0. Consequently, by incorporating stability and eccentricity reduction factors, adjustments are made to existing axial load-carrying capacity prediction formulas, resulting in the calculation formula for the reduction factor R ' c. By measuring the local quality loss rate of the external steel tube of corroded circular CFST columns, it is possible to predict both axial and eccentric load-carrying capacities.