Numerical analysis on mechanical property of concrete filled steel tube reinforced concrete (CFSTRC) columns subjected to ISO-834 standard fire

Abstract

The present study established a numerical investigation on the behavior of concrete filled steel tube reinforced concrete (CFSTRC) columns subjected to fire. A finite element analysis (FEA) model was built to simulate the performance of CFSTRC columns under combined loading and fire. The FEA model was verified by the experimental results of CFSTRC columns subjected to fire. The comparison demonstrated an acceptable accuracy for the proposed FEA model. Afterwards, the FEA model was used to analyze the failure modes, the redistribution of internal force, the changes and development of the stress and strain, and the contact stress between the tube and concrete of CFSTRC columns subjected to fire. Influencing factors that may affect the bearing capacity of the CFSTRC columns subjected to fire were analyzed. The bearing capacity and stiffness of the CFSTRC columns gradually decreased in the fire; the parameters such as the fire duration time, sectional dimension, slenderness ratio, and sectional core area ratio significantly influenced the bearing capacity of the CFSTRC columns. Finally, a simplified calculating formula was proposed to calculate the influence factors of the bearing capacity of the CFSTRC columns subjected to ISO-834 standard fire. The formula-calculated results were well in agreement with the finite element analysis results, which provide a simple and feasible method for evaluating the fire-resistance design of these types of components in practical engineering.