Residual load-bearing capacity of corroded reinforcing steel bars subjected to dynamic loads

动荷载作用下锈蚀钢筋的残余承载能力

• 批准号: 502259457
• 负责人: Professor Dr.-Ing. Michael Raupach
• 金额: --
• 依托单位: Lehrstuhl für Baustoffkunde und Institut für Bauforschung (ibac)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/502259457?language=en
• 关键词: Residual; load; bearing; capacity; corroded

Reinforced concrete structures subjected to fatigue loads, such as bridges, are often exposed to environmental conditions that promote corrosion. Probably the most common type is chloride exposure (de-icing salt on bridge structures, tidal areas in offshore constructions). Since reinforced concrete structures in State II contain cracks, there is a possibility that, especially in combination with dynamic loading and the resulting movement of the cracks, corrosion-promoting substances, e.g. chlorides, can be transported through the crack to the reinforcement and damage it on a local level. The preliminary work as well as the current literature has shown that the fatigue strength of concrete steels is reduced by the simultaneous effect of fatigue and corrosion. However, there is still a lack of fundamental knowledge on the influences of different diameters and exposures on the fatigue resistance. Closely related to this is the influence of the corrosion pit geometry. The aim of the project is therefore to quantify the influence of the corrosion of the reinforcing steel on its fatigue resistance for the exposure classes XC and XD/XS.For this purpose, corrosion pits are generated on different steel diameters in cracked reinforced concrete specimens using different exposure solutions in order to investigate the correlation between the amount of charge flowed and corrosive deterioration in different exposures. In fatigue tests, the correlation between the existing residual cross-section in combination with the morphology of the corrosion pit and the fatigue behavior of bare steel as well as composite specimens is determined. For a closer look at the critical geometric characteristics that reduce fatigue strength, morphologically precisely defined deteriorations are also applied to reinforcing steel bars. By means of the experimental program, mitigation factors for S-N-curves of different diameters and exposures are to be derived.

承受疲劳荷载的钢筋混凝土结构（如桥梁）经常暴露在促进腐蚀的环境条件下。可能最常见的类型是氯化物暴露（桥梁结构上的除冰盐，海上建筑物的潮汐区域）。由于状态II中的钢筋混凝土结构包含裂缝，特别是在与动态载荷和裂缝的产生的移动相结合的情况下，腐蚀促进物质（例如氯化物）可能通过裂缝传输到钢筋并在局部水平上损坏钢筋。初步的工作以及目前的文献表明，混凝土钢的疲劳强度降低的疲劳和腐蚀的同时影响。然而，仍然缺乏关于不同直径和暴露对疲劳强度的影响的基础知识。与此密切相关的是腐蚀坑几何形状的影响。因此，本项目的目的是量化的影响，钢筋的腐蚀对它的疲劳抗力的暴露等级XC和XD/XS。为此，腐蚀坑产生不同的钢筋直径在开裂的钢筋混凝土试件使用不同的暴露溶液，以调查之间的相关性的电荷流动量和腐蚀恶化在不同的曝光。在疲劳试验中，现有的剩余横截面结合腐蚀坑的形态和裸钢以及复合试样的疲劳行为之间的相关性被确定。为了更仔细地观察降低疲劳强度的关键几何特征，还将形态学上精确定义的劣化应用于钢筋。通过实验程序，导出了不同直径和曝光量的S-N曲线的缓和因子。