Effect of temperature on strength and elastic modulus of high-strength steel

This paper presents the effect of temperature on the mechanical properties of high-strength alloy structural Q460 steel. The strength and stiffness properties of steel degrade with temperature and this deterioration has to be properly accounted for in the fire resistant design of steel structures. The strength and stiffness degradation is also influenced by the composition of steel. Because of a lack of data specific to high-strength Q460 steel, design standards assume the high temperature strength variation of Q460 steel to be same as that of conventional mild steel. To overcome this drawback, strength and stiffness properties of Q460 steel were measured at various temperatures in the range of 20-800°C. A relative comparison of measured data indicates that high-strength steel experiences a slower loss of strength and stiffness with temperature than conventional steel. Data generated from the experiments, namely, load-displacement relationships and vibration frequency, were utilized to develop relations for yield strength, tensile strength, and elastic modulus of Q460 steel as a function of temperature. The proposed relations developed specifically for high-strength Q460 steel can lead to better fire resistance prediction of steel structure systems.