Simple Three-Coefficient Equation for Temperature-Dependent Mechanical Properties of Cold-Formed Steels

The objective of this paper is to propose relationships for the reduction in mechanical properties of cold-formed steels at elevated temperature. Predicting the degradation of strength and modulus of cold-formed steels with temperature is critical to enable fire design of cold-formed steel members. Here, the properties of elastic modulus, 0.2% proof stress, 2% stress, and ultimate stress are studied for grades up to and including 550 MPa. Data are collected from the literature as well as from recent tests conducted by the authors at Johns Hopkins University. Steady-state and transient test results in the range of 20°C–1,000°C are analyzed. Retention factors are then proposed for the mechanical properties adopting a standardized format developed through committee work with the American Iron and Steel Institute.