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Title |
Evaluation of Bond Strength of Single Deformed Wire Subjected to Tension
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Authors |
김문길(Mun-Gil Kim) ; 천성철(Sung-Chul Chun) |
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DOI |
https://doi.org/10.4334/JKCI.2021.33.5.491 |
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Keywords |
이형철선; 표면형상; 인발실험; 부착강도; 뽑힘파괴 deformed wire; surface shape; pullout test; bond strength; pullout failure |
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Abstract |
ince deformed wire has a lower carbon equivalent than reinforcing bars, deformed wire is easily welded. There is an increased demand for deformed wire for use as an anchor for connections between non-structural elements and structural elements or steel and concrete . Pullout tests were performed to evaluate the bond performance of straight deformed wire used as an anchor. An experimental variable was an embedded length of deformed wire and reinforcing bar. From the tests, pullout failure occurred in five deformed wires, and in the 19 specimens, actual yield strengths were developed . Three out of five deformed wires where pullout failure occurred had strengths less than the expected values. The bearing area and the shearing area of the deformed wire that affected the bond performance were reduced to 45 % and 34 %, respectively, of those of the reinforcing bar, resulting in a decrease in bond strength. In addition, the relative rib area of the deformed wire increased by 30 % compared with the reinforcing bar, changing the failure mode from splitting to pullout. Based on the test results, an equation for predicting the pullout strength of a deformed wire was developed. The average of test-to-prediction ratios was 0.999 and the coefficient of variation of the ratios was 17.4 %. Based on the developed equation with 5 % fractile coefficient, a design equation of minimum embedment length of the deformed wire was proposed. When the surface deformation rate was 25 %, which is the minimum value allowed in ASTM A1031, the minimum embedment length of the deformed wire increased by 60 % compared with the development length of the reinforcing bar. When the surface deformation rate was 40 %, the minimum length of the deformed wire was the same as the development length of the reinforcing bar.
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