Analysis of rectangular CFT columns subjected to elevated temperature

The current AISC Specification (AISC 360-10) does not specify design equations for estimating the axial compressive strength of concrete-filled steel tube (CFT) columns subjected to elevated temperature. This paper uses a fiber-based analytical approach, which was developed and benchmarked previously by the authors, to investigate the effects of various parameters on the behavior and strength of rectangular CFT columns subjected to elevated temperature. The parameters considered were the steel tube yield stress (Fy), concrete compressive strength (f'c), tube width-to-thickness ratio (B/t), column slenderness ratio (KL/r), and magnitude of temperature. Results from the parametric studies indicate that the axial compressive strength of rectangular CFT columns decreases significantly with increasing temperature. Increasing the concrete compressive strength (f'c) can effectively improve the axial compressive strength of rectangular CFT columns subjected to elevated temperature. While changing the steel tube yield stress (Fy) or the steel tube width-to-thickness ratio (B/t) have smaller influences