Analytical modeling of the standard fire behavior of loaded CFT columns

This paper presents a three-step sequentially coupled analytical approach for predicting the standard fire behavior of concrete filled steel tube (CFT) columns. Numerical models were developed for each step of the approach, namely, (1) fire dynamics analysis, (2) nonlinear heat transfer analysis, and (3) nonlinear stress analysis. 3D finite element models with identical meshes were used for steps 2 and 3. An analytical matrix consisting of fifteen CFT column specimens subjected to standard fire tests by different researchers was selected to verify the numerical models. Sensitivity analyses were conducted to finalize the values of the major model input parameters. This paper summarizes the development of the numerical models, the findings from the sensitivity analyses, and the comparisons of the numerical predictions with experimental results. The verified numerical models (and model input parameters) are recommended for predicting the behavior of CFT columns subjected to fire loading, and for conducting analytical parametric studies.