Experimental investigation of post-fire mechanical properties of Q235 cold-formed steel

Cold-formed steels are commonly used in construction applications. However, there is a lack of understanding on its post-fire mechanical properties. This paper presents an experimental investigation on post-fire mechanical properties of cold-formed steels. The test specimens were cut from flat portion and corners of cold-formed channel sections, which were exposed to temperatures ranging from ambient temperature to 800 degrees C, and then cooled with water and air. The specimens are of grade Q235, with section thicknesses of 1 mm and 2 mm. The stress-strain curves and mechanical properties of the specimens were obtained from tensile coupon tests. Test results of post-fire mechanical properties are presented. Moreover, evolution of microstructure and fracture morphology of specimens with different cooling methods were examined. Finally, predictive equations are proposed for evaluating the post-fire mechanical properties of Q235 cold-formed steel channel sections.