| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1993: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1992: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
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.
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