Creep behavior and model of high-strength steels over 500 MPa at elevated temperatures

Abstract

In fire events, the high-temperature creep behavior of steels may critically affect the fire resistance of steel structures. Most studies related to high-temperature creep behavior have been typically performed for normal structural steels but seldom conducted for high-strength structural steels. In this study, a series of high-temperature steady-state creep tests is conducted on Q550, Q690, and Q890 high-strength structural steels at various stress levels within the 400–800 °C temperature range. The test data obtained demonstrate that the total amount of creep deformation is relatively significant, and the increase in the creep strain rate is considerably rapid at high-temperatures and high-stress levels. The three-stage creep model, together with creep parameters, is proposed to express the creep behaviors of three high-strength steels at various stress levels within the 400–800 °C temperature range. The creep behavior and calibrated creep models obtained in this research can be utilized as a theoretical foundation for accurately predicting the response of high-strength steel structures exposed to fire considering the effect of creep.