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为了对氯离子侵蚀下在役钢筋混凝土桥梁进行全寿命预测,需要选择更为合理的混凝土锈胀开裂时间模型。分别应用单因素变化、多因素变化和敏感性指标对在氯离子侵蚀环境下的10个开裂时间模型进行敏感性分析,得到开裂时间tcr对各输入参数的敏感性大小,并确定出合适的模型。研究结果表明:3种敏感性分析方法的结果基本一致;单因素敏感性分析得出开裂时间tcr对钢筋锈蚀率icorr(jcorr)、锈蚀物密度ρr、氯离子渗透区域δ0、钢筋摩尔质量与锈蚀物的质量之比αm的敏感性较高,这4个参数属于模型中的重要参数;多因素敏感性分析得出tcr对icorr的敏感性增强,同时发现混凝土保护层厚度c、钢筋直径d和混凝土抗拉强度ft变化所引起的tcr变化率的改变也较为显著;敏感性指标分析得出参数c、d和ft的敏感性较单(多)参数分析略有提高;包含以上7个参数,确定文献[4]提出的模型8为适于工程应用的合理模型。
In order to predict the life span of existing reinforced concrete bridges under the chloride ion erosion, a more reasonable model of concrete cracking time of cracking is needed. Sensitivity analysis of 10 models of cracking time under chloride ion erosion was carried out using single factor variation, multivariate analysis and sensitivity index respectively. Sensitivity values of tcr to each input parameter were obtained, and the appropriate model . The results showed that the results of the three sensitivity analysis methods were basically the same. The single factor sensitivity analysis showed that the influence of the cracking time tcr on the corrosion rate icorr (jcorr), corrosion density ρr, chloride ion penetration area δ0, The sensitivity of the mass ratio αm is higher, and these four parameters are important parameters in the model. The multi-factor sensitivity analysis shows that the sensitivity of tcr to icorr is enhanced. At the same time, the thickness of concrete cover c, the diameter d The change of tcr change rate caused by concrete tensile strength ft is also significant. Sensitivity analysis shows that the sensitivity of parameters c, d and ft is slightly higher than that of single (multi) parameter analysis. Including the above seven parameters, It is confirmed that Model 8 proposed in [4] is a reasonable model suitable for engineering application.