锈蚀钢筋混凝土柱残余承载力研究

Residual Loading Capacity of Corroded Reinforced Concrete Columns

沿海及周边地区的钢筋混凝土结构往往因钢筋锈蚀而导致混凝土结构发生开裂破坏、结构承载力降低,严重威胁钢筋混凝土结构的可靠性和安全性。针对氯盐环境中处于服役状态下的钢筋混凝土柱结构的力学性能退化规律进行研究,通过分析钢筋锈蚀引起的材料损伤机理,构建对应的钢筋与混凝土材料退化模型以及构件强度退化模型,计算锈蚀钢筋混凝土柱的残余承载力,并获得锈蚀柱的弯矩-轴力相互作用曲线。计算结果表明,锈蚀钢筋混凝土柱的承载力随锈蚀程度的上升而显著下降,对于大偏心受压情况,当锈蚀程度为6%~10%时,构件的承载力由于钢筋与混凝土界面的黏结强度损失而大幅降低,对于小偏心受压及轴压情况,当锈蚀程度接近5%时,构件的承载力由于受压区混凝土截面的几何损失、钢筋屈服强度降低与横截面面积减小而明显降低。

Reinforced concrete structures in coastal regions often suffer from the corrosion of steel bars caused by chloride ion ingression,resulting in cracking and damage and reduced loading capacity of the concrete structures,which threatens the reliability and safety of structures.In this paper,the degration of the mechanical properties of reinforced concrete columns in service under chlorine salt environments was investigated.Based on the analysis of the mechanism of material damage caused by reinforcement corrosion,the corresponding material degradation model of reinforcement and concrete materials and the degradation model of structural strength were proposed to calculate the residual loading capacity of concrete columns due to material degradation.Then,the interaction curve of the moment and axial load of the reinforced concrete columns with reinforcement corrosion was obtained.The results show that the residual loading capacity of the corroded reinforced concrete columns decreases with the increase of the corrosion rate.In the case of large eccentric compression,when corrosion rate is in the range of 6%~10%,the residual loading capacity has a significant decline due to the loss of bond strength between the reinforcement and the concrete interface.Under small eccentric compression and axial compression,when the corrosion rate is close to 5%,the residual loading capacity has a significant downward trend due to the geometric loss of the concrete section in the compression zone,the decrease in the yield strength of the steel bar and the reduction of the cross-sectional area.