Crack initiation of concrete cover due to corrosion defines the end of functional service life where repair or replacement is required for corroded reinforced concrete (RC) structures. This study provides a comprehensive and critical analysis for the analytical and numerical models of corrosion-induced cover crack initiation for both uniform and non-uniform corrosion. Parametric studies are conducted to investigate the effects of different factors on crack initiation time and crack propagation patterns using a thermal analogy approach defined in three dimensional nonlinear finite element (FE) models. The results show that the type of corrosion products, thickness of interfacial transition zone and rate of corrosion are the parameters that affect crack initiation time the most significantly. The developed FE models are able to study crack initiation and propagation for both uniform and non-uniform corrosion and quantify the extent of concrete damage due to cracks. The FE results show that crack patterns under uniform and non-uniform corrosion differ. Under uniform corrosion, the major crack occurs vertically in the cover. But under non-uniform corrosion, major cracks form diagonally at the location of the pit in the cover. The vertical crack appears later and then becomes the third major crack. The results also show that non-uniform corrosion causes high concentrated pressure at the pits which would lead to earlier cover cracking. It is shown that assuming uniform corrosion may result in non-conservative service life estimation. The efficiency and applicability of the existing empirical models have been analyzed using the outcomes from the finite element models. Recommendations on how to select proper models to estimate crack initiation time have been provided. The outcome of the research provides a reliable approach to predict corrosion-induced cover crack initiation and propagation for RC structures.

由于腐蚀而引起的混凝土保护层的裂纹萌生定义了使用寿命的终止，在该使用寿命中，需要对腐蚀的钢筋混凝土（RC）结构进行修理或更换。这项研究为均匀和不均匀腐蚀的腐蚀引起的覆盖层裂纹萌生的分析和数值模型提供了全面而严格的分析。使用三维非线性有限元（FE）模型中定义的热模拟方法进行参数研究，以研究不同因素对裂纹萌生时间和裂纹扩展方式的影响。结果表明，腐蚀产物的类型，界面过渡区的厚度和腐蚀速率是对裂纹萌生时间影响最大​​的参数。发达的有限元模型能够研究均匀和非均匀腐蚀的裂纹萌生和扩展，并量化由于裂纹对混凝土造成的破坏程度。有限元分析结果表明，均匀腐蚀和非均匀腐蚀下的裂纹形态不同。在均匀腐蚀下，主要裂纹垂直出现在覆盖层中。但是在非均匀腐蚀下，在覆盖层中凹坑的位置对角线会形成大裂缝。垂直裂缝出现较晚，然后成为第三大裂缝。结果还表明，不均匀的腐蚀会在凹坑处引起较高的集中压力，从而导致较早的覆盖层开裂。结果表明，假设均匀腐蚀可能会导致非保守的使用寿命估算。现有经验模型的效率和适用性已使用有限元模型的结果进行了分析。提供了有关如何选择合适的模型来估计裂纹萌生时间的建议。研究结果为预测腐蚀引起的钢筋混凝土结构的覆盖层裂纹的萌生和扩展提供了可靠的方法。