高温后HRBF500细晶粒钢筋力学性能试验研究

试验研究了16组共48根HRBF500细晶粒钢筋在常温和高温冷却作用后（5种温度、3种冷却方式）的力学性能，得到了不同高温冷却作用后细晶粒钢筋的应力-应变关系，分析了屈服强度、抗拉强度、弹性模量、断后伸长率、均匀伸长率、截面收缩率等的变化规律。试验表明：温度作用相对较低时(300℃、400℃、600℃)，细晶粒钢筋力学性能变化不明显；温度作用相对较高时(700℃、900℃)，细晶粒钢筋各项力学指标逐渐退化。根据试验结果，经回归分析建议了高温后细晶粒钢筋屈服强度、抗拉强度、弹性模量、断后伸长率的计算公式。研究成果可作为火灾后采用HRBF500级细晶粒钢筋混凝土结构的损伤评估的依据。图12表6参7

Experimental research on material properties of HRBF500 after high temperature

The mechanical properties of 16 groups and a total of 48 hot rolled bars of fine grains(HRBF) under normal temperature and after high temperature and cooling process (totally 5 high temperatures and 3 cooling methods) were tested and the tensile stress-strain relationships of HRB500 after experiencing various high temperatures were obtained. The variation of yield strength, tensile strength, elastic modulus and average elongation percentage were studied. Experimental results indicate that the mechanical properties of the steel bars do not change obviously when the highest temperatures the steel bars experienced are relatively low (300℃, 400℃ and 600℃, respectively). The mechanical property indices of the steel bars degrade gradually when the highest temperatures the steel bars experienced are relatively high (700℃ and 900℃ respectively). Based on the experimental results, the formulae predicting yield strength, tensile strength, elastic modulus and average elongation percentage of HRBF500 after high temperature were proposed using regression analysis. The conclusions of this research can provide the experimental background for damage evaluation of reinforced concrete structures using HRBF500 after fire.7Refs.In Chinese.