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

Abstract

Cold-formed steels have been commonly applied in construction. However, there is a lack of understanding on its post-fire mechanical properties. This paper presents an experimental investigation into the post-fire mechanical properties of cold-formed steels. The test specimens were cut from the flat portion and corners of cold-formed channel sections, which were exposed to temperatures ranging from ambient temperature to 800°C, and then cooled with water and air. The specimens are of grade Q235, and of thickness 1mm and 2mm. The stress-strain curves and mechanical properties of all specimens were obtained from tensile coupon tests. A comparison of mechanical properties between coupon samples cut from flat portion and corners is presented. Moreover, the evolution of microstructure and fracture morphology of specimens after being cooled by air and water were examined. Finally, predictive equations are proposed for evaluating the post-fire mechanical properties of Q235 cold-formed steel channel sections.

Post‐fire Residual Strength and Ductility of Structural Steels from Hollow Sections

“…In order to decide on the reinstatement or demolition of the surviving structure, the post-fire properties of the steel must be obtained and compared with the provisions of the current standards, so experimental testing is a reliable option. This topic has been studied in previous experimental works on coldformed steels [6][7], structural steels [8][9][10], high-strength steels [11][12] and stainless structural steels [13]. In these works, however, the tested specimens were subjected to a heating and cooling thermal cycle while remained unloaded.…”

“…PFU tests are the post-fire tests traditionally carried out in the literature, as it can be found in previous works [6][7][8][9][10][11][12][13]. In PFU tests, no load is applied, so σt = 0 and μ0 = 0.…”

The shear and flexural behavior of cold-formed steel composite I and U beams

“…In the past few decades, cold-formed steel sections have become increasingly popular for residential, commercial and industrial buildings, due to their convenience in erection, transportation and assembling. However, both stiffness and strength of cold-formed steel materials deteriorate at high temperatures, which causes great concerns in their fire safety in structural applications [1]. The use of cold formed steel in the construction industry is increasing as efforts to introduce a greater degree of pre-fabrication and industrialized processes continue.…”

Improving Corrosion Protection and Friction Resistance of Q235 Steel by Combining Noncovalent Action and Rotating Coating Method

“…Q235 steel is widely used in all aspects of life due to its low price, easy processing, excellent comprehensive performance, and other advantages. 1,2 It is usually applied directly without heat treatment, so the corrosion resistance and friction resistance are very low. 3,4 The coating method has the advantages of low price, simple operation, and good chemical stability; it is one of the most commonly used methods to protect Q235 steel.…”

“…Q235 steel is widely used in all aspects of life due to its low price, easy processing, excellent comprehensive performance, and other advantages. , It is usually applied directly without heat treatment, so the corrosion resistance and friction resistance are very low. , The coating method has the advantages of low price, simple operation, and good chemical stability; it is one of the most commonly used methods to protect Q235 steel. − Waterborne epoxy (WEP) coating meets the requirements of environmental friendliness and corrosion resistance; it has the potential to replace organic epoxy in the future. , However, due to different dispersants and hydrophilic groups contained in waterborne epoxy resins, holes and defects are likely to develop during film formation. It is easily infiltrated by corrosion factors such as Cl – , O 2– , SO 4 2– , etc.…”