硫酸盐侵蚀下轴心受压钢筋混凝土柱应力时变过程的数值分析

针对荷载和硫酸盐耦合作用过程中钢筋混凝土柱的应力分析问题,在已有混凝土内硫酸根离子扩散反应模型的基础上,进一步给出了硫酸盐侵蚀引起的混凝土损伤程度与硫酸根离子浓度及腐蚀时间之间的关系,建立了与损伤程度相关的混凝土腐蚀本构模型及轴压混凝土柱截面应力的计算方法,并通过数值模拟分析了柱截面内硫酸根离子传输、腐蚀损伤程度变化、截面应变和应力分布规律。结果表明:硫酸根离子浓度和混凝土损伤程度在柱截面内呈梯度分布,且受二维交互效应的影响明显;随腐蚀时间的增加,截面损伤区逐渐向内移动且其宽度增加,而混凝土应力在损伤区呈先增加后逐渐降低、在未损伤区基本呈线性增加的趋势。硫酸盐侵蚀过程中,轴压混凝土柱截面应力发生了明显的重分布现象。

Numerical analysis on time-varying process of stress in reinforced concrete column subjected to axial compression and sulfate attack

In order to investigate the stress responses of reinforced concrete column subjected to the couplings of axial compression and sulfate attack,this paper applied an existed diffusion-reaction equation of sulfation in concrete to obtain a relationship between the sulfate-induced damage degree and the ion concentration and the corrosion time.On the basis,a concrete-corroded constitutive model related to the damage degree and a calculating approach for stress responses of concrete under the couplings of axial compression and sulfate attack were proposed.Through numerical solution on these models,the changes of sulfate ion concentration,damage degree,strain and stress in concrete with the corrosion time were analyzed.Results show that the sulfate ion concentration and damage degree has a gradient distribution in concrete,and they are obviously influenced by the two-dimensional interactions in the cross section.With the increase of corrosion time,the damage zone gradually moves inward the cross section,and its width has a gradual increase,and the stress in the damage zone increases firstly and then has a gradual decrease,but in the no damage zone,the stress has a basically linear increase.In the process of sulfate attack,there produces the stress redistribution in concrete under axial compression.