Comparative study between circular and square concrete-filled steel tube (CFST) columns post-fire

The issue of predicting the residual load-bearing capacity of damaged concrete-filled steel tube (CFST) columns subject eccentricities is not widely assessed. The post-fire behavior of CFST columns is experimentally assessed here by running tests with different cross sections (circular and square), subject to eccentric axial loads. Here, the focus is on the influence of cross-sectional shape, load eccentricity (25 and 50 mm), slenderness and fire protective coating parameters on the post-fire bearing capacity of CFST sections. In this paper, the reduction factors are proposed to estimate the residual capacity of the CFST columns with the load eccentricity based on the previous experimental results. The modified design methods based on Eurocode 4 are applied in predicting the residual load-bearing capacity of the concrete-filled hollow tube columns after being exposed to fire. The assessments reveal that the simplified method of Eurocode 4, in the ambient temperature, subject to both the concentric and eccentric loading conditions and yield safe results, thus, a better prediction method.