TENSILE MECHANICAL PROPERTIES RESEARCH OF THREE CONSTRUCTION STEEL BARS IN HIGH STRAIN RATE

Reinforced concrete structure usually suffers static load, but it will probably suffer dynamic load in terrorist attacks, explosion of gas pipeline, and other special circumstances. Therefore, research on the construction steel bars is important for researching the dynamic mechanical response of the reinforced concrete structure. In this paper, the experimental study of dynamic tensile mechanical properties of three commonly used construction steel bars (HPB235, HRB335 and HRB400) was carried out within the strain rates of 400 s^-1~2000 s^-1, using rotating disk impact tensile test system. According to the experimental data, the influence of strain rate on the yield strength was analyzed and the original Johnson-Cook constitutive model was modified. The suitable Johnson-Cook constitutive model parameters were derived to describe the stress-strain curve of three steel bars. The research results show that:the yield stress of three kinds of construction steel bars increases with the increase of strain rate; the construction steel bar with low static yield stress is more strain rate-sensitive than that with high static yield stress; the modified Johnson-Cook Constitutive model is suitable for describing the stress-strain relationship of three steel bars.