氯盐环境下混凝土中锈蚀钢筋力学性能研究

基于试验、仿真及理论分析探讨了氯盐环境下混凝土中锈蚀钢筋的力学性能退化规律及其影响机理。通过对取自历时两年干湿循环混凝土试件中的214根锈蚀钢筋进行拉伸试验表明：当锈蚀率较小时，钢筋名义强度随之增加近乎线性下降；当锈蚀率较大时，钢筋名义、等效强度及延性均随之增加而下降；钢筋的屈服平台随锈蚀不均匀性增大逐渐缩短甚至消失；钢筋断裂形态随局部锈蚀特征变化；同等条件下细直径钢筋力学性能对锈蚀更敏感。就试验现象进行理论和仿真分析表明：钢筋的实际抗拉强度在锈蚀前后并无显著变化；钢筋名义强度的降低，主要是由于锈损引起横截面积减小导致抗力减小而造成的；锈蚀引起的钢筋面积减小、缺口效应及附加偏心作用是导致其伸长率减小的主要原因；附加弯矩作用是钢筋力与变形关系曲线中屈服平台缩短、消失的主要原因。

Research on mechanical properties of corroded steel bar in concrete under chloride environment

Based on the analysis of experiment, theory and simulation, The rule of the residual properties of corroded reinforcing bars in chloride environment is discussed, and the cause is analyzed in principle. 214 corroded bars were taken out from the RC specimens after two years wet-dry cycle test. The tensile experiment results on them show that: when the corrosion ratio is small, The nominal strength of steel bars falls almost linearly with the corrosion ratio increasing; when the corrosion ratio is large, the nominal and the equivalent strength fall with it increasing, so is ductility; the yield plateau decreases, even disappears as the corrosion is more and more non-uniform. The Fracture Morphology changes with local corrosion characters. Under the same conditions, the mechanical properties of corroded small-diameter bars are degraded more than that of large ones. From the analysis of theory and simulation based on experiment, the following conclusions are found: the actual tensile strength of reinforcing bars changes not remarkably pre and post the corrosion; The nominal tensile strength is decreased, chiefly because the cross sectional area decreased after corrosion that lead to the decrease of resistance; the cross sectional area decreased , notch effect and the additional eccentric force due to corrosion have a remarkable influence on the elongation of steel bars; It is mainly attributed to the additional moment for the local non-uniform corrosion that the yield platform of uniaxial tension is shortened, even disappear.