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Title |
Statistical Analysis on Corrosion and Estimation of Probability on Fracture for Corroded Strand of a Post-Tensioned Bridge on Service
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Authors |
조선두(Seon-Doo Jo) ; 권승희(Seung-Hee Kwon) ; 이윤(Yun Lee) ; 김철영(Chul-Young Kim) |
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DOI |
https://doi.org/10.4334/JKCI.2017.29.6.545 |
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Keywords |
포스트텐션 ; 강연선 ; 부식 ; 부식량 ; 염화물 농도 post-tensioned ; strand ; corrosion ; pit depth ; chloride concentration |
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Abstract |
In this study, the strand specimens and grout samples were extracted from the position of actual fractured tendons and its vicinity in a post-tensioned bridge on service, and the pit depths of the strand specimens and the acid-soluble chloride concentration of the grout sample were measured. The effect of the chloride concentration of the grout on the corrosion of the strands was investigated based on the statistical analysis, and the probability on the strand was estimated by the chloride concentration of the grout. The probability density decreases linearly as the increase of the pit depth of a logarithmic scale. The slope of the probability density for pit depths in a logarithmic scale measured exceeding the critical chloride concentration of 5,000 ppm was 0.568 (outer wire) and 1.041 (center wire), which was smaller than the slope of 1.806 (outer wire) and 2.638 (center wire) at the low chloride concentration range of less the 500 ppm. This means that the higher the concentration of chloride, the higher the probability of larger pit depth. The probability on one wire fracture, either center wire or outer wire, was estimated to be 2.29250 % at the chloride concentration over 5,000 ppm, and 0.10325 % at the chloride concentration below 500 ppm. The probability on two wires fracture, either center wire and one outer wire both or two outer wires, was estimated to be 0.11062 % at the chloride concentration over 5,000 ppm, and 0.00019 % at the chloride concentration below 500 ppm.
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