Experimental and theoretical investigation on the residual mechanical performance of HRB600 steel bars after high-temperature exposure

Résumé fourni par la source

Reinforcing bars are recognized as the primary load-bearing components in concrete structures, responsible for bearing the main tensile stresses. In this study, the mechanical properties of reinforcing bars with different strength grades after exposure to elevated temperatures (25°C to 800°C) were investigated, and the variation patterns of stress-strain curves, elastic modulus, yield strength, ultimate strength, elongation, and shrinkage were systematically analyzed. The results indicate that the shear lip region on the fracture surface of steel bars becomes more regular with increasing temperature. When the exposure temperature does not exceed 600°C, minimal changes in the mechanical properties of steel bars are observed after cooling. At 800°C, the yield plateau in the stress-strain curve is significantly lengthened, while a marked decrease in yield strength is observed. Furthermore, through combined first-principles calculations and microstructural analysis, it was revealed that exposure to 800°C intensifies the thermal motion of atoms in Fe cells. Density of states (DOS) analysis indicated that electron orbital hybridization near the Fermi level is weakened, which diminishes the covalent nature of metallic bonds and consequently leads to a reduction in strength. After high-temperature exposure, higher yield strength and ultimate strength are retained by high-strength steel bars, and sufficient ductility is also maintained. Based on the experimental results, a method for evaluating the mechanical properties of HRB600 high-strength steel bars within the high-temperature range up to 800°C has been established.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.