Mechanical properties of cold-formed steel at elevated temperatures

Abstract

This paper presents the mechanical properties data for cold-formed steel at elevated temperatures. The deterioration of the mechanical properties of yield strength (0.2% proof stress) and Young's modulus of elasticity are the primary properties in the design and analysis of cold-formed steel structures under fire. However, values of these properties at different temperatures are not well reported. Therefore, both steady and transient tensile coupon tests were conducted at different temperatures ranged approximately from 20 to 1000°C to obtain the mechanical properties of cold-formed steel structural material. This study included cold-formed steel of grade G550 and G500 with plate thickness of 1.0 and 1.9mm, respectively. Stress-strain curves at different temperatures are plotted. In addition, curves of elasticity modulus, yield strength obtained at different strain levels, ultimate strength and thermal elongation versus different temperatures are also plotted and compared with the results obtained from the Australian, British and European standards. The test results obtained from this study are also compared with the test results predicted by other researchers. A unified equation for yield strength and Young's modulus of cold-formed steel at elevated temperatures is proposed in this paper. It is shown that the proposed equation accurately predicted the yield strength and Young's modulus compared with the test results.