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EVALUATION OF RESIDUAL CAPACITY OF CONCRETE STRUCTURES DEMAGED BY SALT ATTACK

盐蚀破坏混凝土结构剩余承载力评估

基本信息

批准号：
04650421
负责人：
MARUYAMA Kyuichi
金额：
$ 1.34万
依托单位：
NAGAOKA UNIVERSITY OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

The research project consisted of three phases, such as (1) to examine the relationships among the cumulative electric current, the amount of corrosion of steel bar and the crack width on the surface of concrete using an erosion test, (2) to examine the deterioration of flexural capacity of beams by corrosion of steel bars under static loading, and (3) to examine the fatigue strength of beams with corrosion of steel bars.As for the first phase of project, the Faraday's law was acknowledged for the relationship between the cumulative electric current and the amout of corrosion of steel bar, and the crack width on the surface of concrete was observed linearly increased with the amout of corrosion. Stirrups did not influence the relationships so much.Unless the crack width on the surface of concrete exceeded 0.3mm, the mechanical behavior of RC beams under static loading was not reduced by corrosion of steel bars. Even if lapped splices were provided at the mid span, the properly arranged stirrups made the behavior of beams as they were. When the anchorage of steel bars is sufficiently proved, the reduction of capacity due to longitudinal cracks may be less than 30 %.The fatigue behavior of beams was greatly influenced by corrosion of steel bars. In particular, corroded steel bars are sensitive to stress concentration, and are easy to reduce the fatigue resistance. Under repeated loading, all beams with corrosion of steel bars failed by the rupture of steel bars irrespecitive to the amount of corrosion. The fatigue life, however, depended upon the amount of corrosion.

该研究项目分为三个阶段，例如（1）通过侵蚀试验研究累积电流、钢筋腐蚀量和混凝土表面裂缝宽度之间的关系；（2）研究静态荷载下钢筋腐蚀对梁抗弯能力的恶化；（3）研究钢筋腐蚀梁的疲劳强度。累积电流与钢筋腐蚀量之间的关系采用法拉第定律，观察到混凝土表面裂缝宽度随腐蚀量线性增加。箍筋对这些关系的影响不大。除非混凝土表面的裂缝宽度超过0.3mm，静载下钢筋混凝土梁的力学性能不会因钢筋腐蚀而降低。即使在跨中提供搭接接头，正确布置的箍筋也会使梁的行为保持原样。当钢筋的锚固性得到充分证明时，由于纵向裂缝而导致的承载力下降可小于30%。钢筋的腐蚀对梁的疲劳性能影响很大。特别是锈蚀的钢筋对应力集中敏感，容易降低抗疲劳能力。在重复荷载作用下，无论腐蚀程度如何，所有发生钢筋腐蚀的梁均因钢筋断裂而失效。然而，疲劳寿命取决于腐蚀量。