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

钢筋锈蚀对钢筋混凝土结构的结构性能和耐久性有很大影响。然而，由于构件内部锈蚀程度的差异和结构内部各向异性的存在，钢筋锈蚀程度与结构性能之间的关系一直没有得到充分的阐明，本研究通过对实际结构中钢筋锈蚀截面面积的测量，定量地揭示了钢筋锈蚀的变化规律。此外，通过再现钢筋锈蚀的不同变化，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，锈蚀钢筋的强度可以用最大截面损失来估算。在结构性能方面，采用钢筋横截面最大损失值准确估算了结构的第一屈服荷载，但受锈蚀的空间变异性影响不大。在第一次屈服后，钢筋局部锈蚀对结构性能的影响随钢筋直径、钢筋数量和锈蚀位置的不同而不同。特别是锈蚀部位钢筋与混凝土之间的粘结应力传递机制对钢筋混凝土构件的承载能力有较大影响。在此基础上，提出了退化钢筋混凝土构件和结构的结构承载能力简化评估的概念。针对钢筋混凝土结构中钢筋锈蚀的变化，开发了钢筋混凝土结构全寿命周期管理系统。

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.