Mechanical properties and creep strain of high strength steel at elevated temperatures

For evaluating the fire resistance of steel structures, high-temperature properties of steel are to be specified as input data. The properties of steel not only vary with temperature but also the extent of variation is influenced by the type and grade of steel. This paper presents a comprehensive tension test on temperature-dependent properties of HSS, including yield strength, elastic modulus and creep strain of Q460, Q690 and Q960 steel at elevated temperature. The test results were compared with the results of other high-strength steel types such as S460, Q550, S690, Q890 and S960 steels reported in previous studies as well as the mechanical properties recommended in applicable design codes or standards. The comparison showed that the effect of temperature on the mechanical properties among different types of high-strength steels are different. Based on the test data, stress-strain relationships and creep models were proposed for Q460, Q690 and Q960 steel, respectively. In order to conveniently determine the mechanical properties of HSS in fire resistance design, new predictive equations for evaluating the material properties of HSS at elevated temperatures were presented.