FE analysis of fire-resistance performance of concrete filled steel tubular columns under different loading cases

There are two main loading cases for concrete filled steel tubular (CFST) columns in the real application, i. e. 1) loading applied simultaneously on the core concrete and steel tube, 2) loading only applied on the core concrete, also known as steel tube confined concrete (STCC) columns. With the proper material models under fire loading, ABAQUS finite element program was used to analyze the fire-resistant performance of CFST columns under these two loading cases, accounting for the interaction behavior between steel tube and core concrete. The analysis results indicate that compared with those under the first loading case, the CFST columns under the second loading case exhibit different expansion behavior and fire resistance. Parametric analysis was then conducted to investigate the influence of factors on the fire-resistant performance of STCC columns exposed to ISO-834 standard fire conditions, including load ratio, slenderness ratio, section dimensions, load eccentricity ratio, strength of steel and concrete, etc, conclusions obtained in this paper will provide some reference for the further research.