Elevated-temperature mechanical properties of high strength structural steel S460N: Experimental study and recommendations for fire-resistance design

Fire-resistance design is one of the most important considerations when structural engineers conduct design of steel structures. As a basis of analyzing fire performance of steel structures, elevated-temperature mechanical properties of structural steels are significant for practical design. The recommendations of current European, American, Australian and British standards were mainly obtained from mild steels, which are in question when used to conduct fire-resistance design of high strength steel structures. In order to reveal the elevated-temperature mechanical properties of high strength steel S460N, tensile tests were conducted at various temperatures ranged 20–700 °C. The elevated-temperature reduction factors of elastic modulus, yield and ultimate strengths of S460N were obtained and compared with current design standards and available literature. According to the comparison between this research result on S460N and the available research results in literature on S460N, S460M and various mild steels, it is found that the deterioration of mechanical properties of structural steels at elevated temperature is dependent on steel grades. Thus the recommendations in current design standards are not applicable to high strength structural steels. Further unique predictive equations for the deterioration of high strength structural steel S460 at elevated temperatures were proposed and validated with available literature.

► Mechanical properties of HSS S460N at elevated temperature are obtained. ► Elevated-temperature properties of steels are dependent on steel grades. ► No current design standard is applicable to HSS S460N at elevated temperatures. ► Accurate predictive equations are proposed for evaluating HSS S460 in fire. ► Research results offer information for revision of current design standards.