Post-fire behavior of cold-formed titanium-clad bimetallic steel angle section stub columns

This study included a series of experiments and a detailed numerical analysis to reveal the cross-sectional behaviors and residual compression ultimate capacities of cold-formed titanium-clad bimetallic steel (TCBS) angle section stub columns (ASSCs) following exposure to high temperatures. Four cold-formed TCBS ASSCs with different geometric dimensions were tested. The exposure temperature included 20 °C, 700 °C, and 900 °C. After experiment, a comprehensive numerical analysis was carried out, wherein 200 finite element models were included. Given the lack of specialized design approaches for cold-formed TCBS structures, the applicability of conventional design approaches for carbon steel structures to cold-formed TCBS ASSCs subjected to high temperatures was assessed, where the design approaches in EN 1993-1-1, AISI 100, and the Direct Strength Method were considered. It was found that the existing design approaches for post-fire cold-formed TCBS ASSCs lacked precision. Hence, modifications to the design approach in EN 1993-1-1 were proposed to improve the accuracy on the prediction of the residual compressive ultimate capacities of cold-formed TCBS ASSCs following exposure to high temperatures. This provided the foundation for evaluating the post-fire serviceability of cold-formed TCBS structures.