HRBF500钢筋高温后力学性能试验研究

EXPERIMENTAL RESEARCH ON MECHANICAL PROPERTIES OF HRBF500 AFTER HIGH TEMPERATURES

通过拉伸试验,研究20,100,200,300,400,500,600,700,800,900,1 000℃高温冷却后HRBF500钢筋屈服强度、极限强度、弹性模量、延伸率和受拉应力-应变关系的变化规律。结果表明,高温冷却后细晶钢筋,温度历程低于500℃时,钢筋的力学性能变化不明显;高于500℃时,随温度历程的升高,钢筋的应力-应变关系曲线逐渐软化,钢筋的各项力学指标逐渐退化。基于试验数据,提出了高温后500 MPa细晶粒钢筋屈服强度、极限强度和弹性模量随温度变化的计算公式,为开展细晶粒钢筋结构抗火性能分析及火灾后损伤评估提供基础性素材。

The mechanical properties of hot rolled bars of fine grains （HRBF500） after high temperatures were studied experimentally. Eleven groups（33 specimens） were tested after temperatures of 20,100,200,300,400,500,600,700,800, 900,and 1000℃, respectively. The variation of yield strength, ultimate strength, elastic modulus, elongation and tensile stress-strain relationship of the HRBF500 at elevated temperatures were investigated and discussed. The results show that the variation of the mechanical property of HRBF500 is not obvious when the highest temperature the reinforcing bar reached is less than 500℃; while the stress-strain curves of reinforcing bar become more ductile and the mechanical property indexes of the reinforcing bar degenerate gradually when the highest temperature is more than 500℃. Based on the results of the experiment, the calculation formulas for yield strength, ultimate strength, elastic modulus after high temperatures are proposed. All can be served as basic data for analysis of fire resistance and after-fire damage evaluation of structures with hot rolled bars of fine grains （HRBF500）.