Stress and deformation analysis of double cold-formed steel columns under non-uniform temperature conditions

This study delves into the intricate stress and deformation behavior exhibited by double cold-formed thin-walled steel columns when subjected to non-uniform temperature conditions. By employing a multifaceted approach that encompasses theoretical analysis, rigorous experimental testing, and fire simulation, the mechanical properties of these steel columns across varying temperature spectra are meticulously examined. In the experimental phase, Q355 steel plates of 1.5 and 3 mm thicknesses are subjected to high-temperature tensile tests and fire resistance evaluations. The results unveil a stark reality: as temperatures escalate, both the yield strength and ultimate strength of the steel columns diminish precipitously while their capacity for deformation amplifies markedly. For instance, at 800 °C, the yield strength of the 1.5 mm thick steel plate stands at 384 MPa, with an ultimate strength of 519 MPa. However, this strength falters as the temperature soars to 1500 °C, with the yield strength plummeting to 303 MPa and the ultimate strength to 602 MPa. The study further employs finite element analysis, utilizing a segmented heating model to emulate the temperature gradient during a fire scenario. This simulation provides a detailed examination of the deformation of steel columns at various temperatures. The comparison between the simulation outcomes and experimental data reveals a remarkable degree of accuracy under extreme temperature conditions, thereby affirming the model’s reliability. This study innovatively integrates theoretical analysis, experimental testing, and fire simulation to systematically investigate the complex stress and deformation behavior of double cold-formed thin-walled steel columns under non-uniform temperature conditions. These insights are indispensable for the design of steel structures and fire safety assessments, offering a pivotal foundation for the advancement and optimization of steel structures operating under extreme conditions.