The repair of fire-damaged thin-walled rectangular concrete-filled steel tubular (CFST) columns in engineering
structures after fire exposure requires the assessment of their residual strength and stiffness. Existing numerical
models have not accounted for the effects of local buckling on the post-fire behavior of CFST columns with
rectangular thin-walled sections. This paper describes a nonlinear post-fire simulation technique underlying the
theory of fiber analysis for determining the residual strengths and post-fire responses of concentrically loaded
short thin-walled rectangular CFST columns accounting for progressive local buckling. The post-fire stress-strain
laws for concrete in rectangular CFST columns are proposed based on available test data and implemented in the
theoretical model. An innovative numerical scheme for modeling the progressive local and post-local buckling of
CFST thin-walled columns is discussed. The nonlinear post-fire simulation model is verified by experimental data
and then used to investigate the significance of local buckling, material strengths and width-to-thickness ratio on
the post-fire responses of CFST stub columns. The proposed post-fire computer model is shown to be capable of
predicting well the residual stiffness and strength of concentrically loaded thin-walled CFST columns after fire
exposure. A design formula is proposed that estimates well the post-fire residual strengths of CFST columns.
Computational results presented provide a better understanding of the post-fire behavior of CFST columns
fabricated by thin-walled sections incorporating local and post-local buckling.