Mechanical and ductile fracture performances of high strength structural steel Q690 after a fire: experimental investigation

Abstract

Abstract In this study, a total of 26 tests were conducted to investigate the post-fire mechanical and ductile fracture performances of high strength structural steel (HSSS) Q690. The purpose of this experimental research is to evaluate the residual strength and residual ductility of the HSSS Q690 after a fire. Tensile coupons obtained from the HSSS Q690 sheets were heated to various temperatures up to 900℃, and then were cooled down in air to ambient temperature. Tensile coupon tests were carried out to obtain their post-fire nominal stress-nominal strain curves, post-fire true stress-true strain curves, corresponding mechanical properties (including yield stress, ultimate strength, Poisson’s ratio, elastic modulus and elongation), and ductile fracture behaviors. Test results showed that the HSSS Q690 can keep the unchanged mechanical performances after it experiences temperatures up to 600℃. And then a set of prediction equations are obtained to evaluate the post-fire mechanical performances of such high strength steels. The results presented in this experimental study are expected to lead to accurate assessing the post-fire performances, including mechanical performances and ductility performances, of the HSSS Q690.