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Title |
Experimental Evaluation on Bond Strengths of Reinforcing Bar in Coils with Improved Machinability during Straightening Process
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DOI |
https://doi.org/10.4334/JKCI.2013.25.1.053 |
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Keywords |
코일철근 ; 부착 ; 마디 ; 직선화 가공 reinforcing bar in coils ; bond ; rib ; straightening process |
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Abstract |
A new deformation of reinforcing bar in coils was proposed to improve a machinability of straightening process, which has crescent-shaped transverse ribs with an inclination angle of 50 degrees, a crest width of 0.15db, and a flank inclination of 55 degrees. The proposed deformation can increase contact area between a surface of re-bar and a groove of a roller during a straightening process and, therefore, it might reduce a damage of ribs, improve a final straightness, and enhance an efficiency of the straightening process. Splice tests were conducted to evaluate bond strengths of three types of re-bar in coils including the proposed re-bar, of which the inclination angles of transverse ribs were 50, 60, and 90 degrees, respectively. Test results show that the re-bars in coils have higher bond strengths than predicted strengths by equations of Orangun et al., ACI 408, and KCI by at least 10%. Correlation coefficients of bond strengths between a straight bar and re-bars in coils are 0.94 and more. Consequently, equations of the KCI code for determining development and splice lengths can be applied to the tested re-bars in coils.
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