基于3参数Weibull分布钢筋混凝土盐腐蚀环境中可靠性寿命分析

为研究钢筋混凝土在耦合盐环境中的腐蚀劣化规律及寿命分布，将钢筋混凝土试件置于0.32 mol·L?1 NaCl和0.4 mol·L?1 MgSO₄盐溶液中，利用电化学工作站定期无损检测，以极化曲线、交流阻抗图谱及电化学参数指标进行耐久性分析，选择3参数Weibull进行可靠性建模，通过Anderson-Darling法（A-D）进行先验假设检验，采用相关系数优化法(CCOM)、极大似然法(MLM)及矩估计法(MEM)进行参数估计，综合可靠度曲线、密度曲线、失效率曲线对钢筋混凝土在氯盐、硫酸盐、镁盐腐蚀环境中的寿命进行分析，研究结果表明:腐蚀离子综合作用下，极化曲线逐渐向腐蚀电流密度增大和负电位方向移动，交流阻抗图谱不断左移并向阻抗实部收缩，钢筋锈蚀发生的阻力逐渐减小，概率逐渐增大。可靠性寿命曲线初期保持不变，后期加速下降，密度曲线呈单峰对称状，失效率曲线初始基本保持不变，后期线性增加。3种参数估计方法中，CCOM和MLM参数估计值相近且稳定准确，所得可靠性寿命曲线相似，MEM参数估计值误差较大，对于钢筋混凝土加速试验得到的小样本失效数据建议用CCOM和MLM进行参数估计，并进行可靠性寿命分析。C35钢筋混凝土在硫酸镁及氯化钠腐蚀环境中的可靠性寿命周期约为760 d。 

Reliability life analysis of reinforced concrete in a salt corrosion environment based on a three-parameter Weibull distribution

To study the corrosion law and life distribution of reinforced concrete in a coupled salt environment, the reinforced concrete specimens were placed in 0.32 mol·L?1 NaCl and 0.4 mol·L?1 MgSO₄ salt solutions. The performance of reinforced concrete was tested regularly using an electrochemical workstation. The durability was analyzed through a polarization curve, an AC impedance spectrum, and electrochemical parameters. A three-parameter Weibull distribution was selected for reliability modeling, and a prior false test was performed by the Anderson-Darling (A-D) method. The parameters were estimated by the correlation coefficient optimization method (CCOM), maximum likelihood method (MLM), and moment estimation method (MEM). The reliability curve, density curve, and failure rate curve were each used to analyze the life of reinforced concrete in chloride, sulfate, and magnesium-based corrosion environments. Results show that under the combined action of corrosion ions, the polarization curve gradually moves toward increasing corrosion current density and negative potential, and the AC impedance spectrum moves to the left and shrinks to the real part of the impedance. The resistance of steel bar corrosion gradually decreases whereas the probability gradually increases. The reliability curve is unchanged at the initial stage and rapidly decreases at the later stage. The density curve is symmetric with a single peak, and the failure rate curve remains unchanged at the initial stage and increases linearly at the later stage. Among the three-parameter estimation methods, CCOM and MLM parameter estimation values are similar, stable, and accurate, and the obtained reliability curves are similar. It is suggested that CCOM and MLM should be used for parameter estimation and reliability analysis of small sample failure data that is obtained from an accelerated test of reinforced concrete. The reliability life of C35 reinforced concrete in magnesium sulfate and sodium chloride corrosion environments is about 760 d.