Evaluation on spatial variability of corrison of steel bar in marine concrete structure

混凝土中钢筋的锈蚀对钢筋混凝土结构的性能和耐久性有很大影响。然而，钢筋锈蚀程度和结构性能之间的关系还没有得到充分的明确，因为在结构构件内的腐蚀和结构内的各向异性的变化，在本研究中，通过测量腐蚀钢筋的横截面面积从真实的结构，钢筋锈蚀的变化定量明确。此外，通过模拟钢筋锈蚀的各种变化，试验研究了锈蚀变化对钢筋混凝土结构力学性能的影响，结果表明，锈蚀钢筋的强度可用最大截面损失来估算。在结构性能方面，首次屈服荷载可以通过钢筋截面面积的最大损失进行准确评估，但腐蚀的空间变化对首次屈服荷载的影响不大。在第一次屈服后，钢筋局部腐蚀对结构性能的影响根据钢筋的直径和数量以及腐蚀的位置而变化。锈蚀钢筋与锈蚀部位混凝土之间的粘结应力传递机制对构件的承载力有重要影响。因此，这是不可能的，以估计在截面面积的钢筋的最大损失的结构性能。根据这些结果在本研究中得到的，最后，简化评估的概念，提出了关于退化的钢筋混凝土构件和结构的结构能力。考虑到钢筋混凝土结构中钢筋锈蚀的变化，开发了全寿命管理系统。

Corrosion of steel reinforcement embedded in concrete has a great influence on structural performance and durability of reinforced concrete(RC) structures. However, the relationship between the degree of steel reinforcement corrosion and structural performance has not been made clear adequately because of wide variations in corrosion within a structural member and anisotropy within a structure.In this study, through measurement of the cross-sectional areas of corroded steel bars taken from real structures, variations in corrosion of steel reinforcement were quantitatively made clear. Moreover, an influence of the variation of corrosion on mechanical properties of RC structures was experimentally investigated by reproducing various variations of steel reinforcement corrosion.As a result, it was made clear that strengths of corroded steel reinforcement are estimated by using the maximum cross-sectional loss. Regarding the structural performance, the first yield load was accurately evaluated by using the maximum loss in cross-sectional area of steel reinforcement, but it was not greatly influenced by the spatial variation of corrosion. After the first yield, an influence of localized corrosion of steel bars on structural performance was varied depending on the diameter and number of steel reinforcement and position of corrosion. In particular, the load-carrying capacity of RC member was influenced by the mechanism of bond stress transfer between corroded steel reinforcement and concrete at the corroded position. Therefore, it was not possible to estimate the structural performance by the maximum loss in cross-sectional area of steel bar.Based on these results obtained in this study, finally, the concept of simplified assessment was proposed regarding the structural capacity of deteriorated RC members and structures. The life-cycle management system was developed taking into account the variations in corrosion of steel bars in RC structures.