中文摘要：

为研究锈蚀疲劳后混凝土中钢筋的力学性能退化规律,对锈蚀钢筋混凝土梁疲劳破坏后取出的梁内主筋进行轴向拉伸试验,结合试验得到的锈蚀疲劳钢筋的应力-应变曲线,定量化地提出了锈蚀疲劳后混凝土中钢筋的本构关系模型,并对模型计算值与试验实测值进行对比验证.试验结果表明,未锈蚀钢筋在疲劳循环200万次后表现出与原状钢筋相同较好的延性破坏特征,疲劳作用对未锈蚀钢筋的力学性能没有实质影响;锈蚀疲劳后钢筋的应力-应变曲线发生了显著变化：屈服台阶特征改变、延伸率减小、屈服强度降低,变化幅度的大小与锈蚀疲劳程度有关,软钢不同程度地硬化;疲劳裂纹的出现使得钢筋在极低的延伸率下即突然拉断破坏,强度大幅降低,延性几乎完全丧失.

英文摘要：

In order to investigate the mechanical behavior of steel reinforcing bars（ rebars） after corrosion fatigue,axial tensile tests of rebars which were removed from corroded reinforced concrete（ RC） beams after fatigue loading tests was carried out. Combined with the experimentally obtained stress-strain curves of the rebars after corrosion fatigue,constitutive relation model for the rebar after corrosion fatigue was quantitatively presented. And the model was verified by comparing the calculated values with the test ones. Test results show that,after cyclic loading to 2million times,uncorroded rebars have the same ductile failure characteristics as the original ones without corrosion fatigue. Fatigue effect has no substantial influence on mechanical behavior of uncorroded rebars. Stress-strain curves for the rebars after corrosion fatigue changed obviously： characteristics of yield plateau changed,percentage of elongation shortened and yield strength decreased. The magnitude of variation correlated with the degree of corrosion fatigue. Mild steel changed into hard steel to varying degrees. The emergence of fatigue crack in rebar caused tensile failure in very low percentage of elongation,great reduction of yield strength and almost complete loss of ductility.