Numerical prediction of fire resistance of Concrete-Filled Steel Tubular (CFST) columns protected by intumescent fire coating

Abstract

Concrete-filled steel tubular (CFST) columns provide high load-bearing capacity, reduced c/s, and better fire resistance compared to hollow steel columns due to the presence of concrete. Usually, when CFST columns are filled with concrete and subjected to high load levels, they require additional fire protection for specific fire-resistance rating requirements. Intumescent coating (IC) is one of the widely used methods for protecting steel structures because of its high fire protection capacity. It has additional advantages over conventionally used fire protection materials, particularly being lightweight and having a good aesthetic appearance. Previous experimental studies indicate lower temperature rise rates in CFST columns with IC protection compared to unprotected CFST columns. This study introduces a sectional analysis-based numerical model developed to predict the temperature field and fire resistance of CFST columns. The model integrates nonlinear heat transfer analysis and load-deflection analysis, which are validated against available experimental data. Additionally, numerous CFST column models were simulated to assess the impact of various parameters on fire resistance. The findings highlight the significant influence of parameters such as steel ratio, concrete compressive strength, cross-sectional dimension, load eccentricity, slenderness ratio, and intumescent coating thickness on the fire resistance of CFST columns.