高应变率下HRB600高强钢筋力学性能试验研究

钢筋混凝土结构抗震分析中应该采用钢筋材料的动态塑性本构模型,HRB600高强钢筋作为新一代建筑钢材,尚无其在高应变率下的力学性能研究。首先进行了HRB600高强钢筋拉伸力学性能试验,得到了不同应变率下的HRB600高强钢筋力学性能数据,屈服强度最大提高11.5%,极限强度最大提高8.9%,然后拟合得到HRB600高强钢筋在高应变率下的强度提高系数表达式。研究结果表明:随着应变率的增大,钢筋的屈服强度和极限强度均得到提高;在相同应变率条件下,钢筋屈服强度动力提高系数大于极限强度动力提高系数;相比较低强度钢筋,应变率敏感性明显低于HPB235、HRB335及HRB400,但与HRB500钢筋相差较小,而极限强度应变率敏感性明显高于低强度钢筋;基于试验数据得到的HRB600高强钢筋在高应变率下的动态塑性本构模型,与试验值吻合较好。研究成果可作为HRB600高强钢筋混凝土结构抗震评估的依据。

Experimental Study on Mechanical Properties of High Strength Steel Bar HRB600 under High Strain Rate

The dynamic plastic constitutive model of steel rebar should be used in seismic analysis of reinforced concrete structures. As a new generation steel rebar, there is no published research on the mechanical properties of HRB600 under high strain rate. In this paper, the tensile mechanical properties of HRB600 under different strain rates were studied, and the mechanical properties of HRB600 under different strain rates were obtained. The yield strength increased by 11.5% and the ultimate strength increased by 8.9%. The expression of improvement coefficient of HRB600 under high strain rate was proposed. The results show that the yield strength and ultimate strength of reinforcement improve with the increase of strain rate. Under the condition of the same strain rate, the improvement coefficient of yield strength is greater than that of ultimate strength. Compared with low strength steel, the sensitivity of strain rate of HRB600 is significantly lower than that of HPB235, HRB335 and HRB400. But there is little difference between HRB600 and HRB 500. The ultimate strain rate sensitivity of HRB600 is significantly higher than that of the low strength steel bars. On the basis of the experimental data, a dynamic plastic constitutive model of HRB600 under high strain rate is obtained. The research results can be used as the basis for seismic evaluation of HRB600 high strength reinforced concrete structure.