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Title |
Development Length Effects of High Strength Headed Bar
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Authors |
문정호(Jeong-Ho Moon) ; 오영훈(Young-Hun Oh) |
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DOI |
http://dx.doi.org/10.11112/jksmi.2015.19.5.075 |
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Keywords |
확대머리 이형철근 ; 정착길이 ; 설계기준항복강도 ; 철근파단 ; 블록파괴 ; 뽐힘파괴 Headed deformed bar ; Development length ; Anchor ; Specified yield strength ; Tension failure ; Blockout ; Pullout |
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Abstract |
An experimental study has been carried out to examine development length effects for high strength headed deformed bars. Current design codes limit the specified yield strength of headed bars to 400 MPa. Such the limit is due to the lack of experimental studies on headed bars made of high strength materials. Thus a test program was planed with headed bars with the yield strength of 600 MPa. The threaded head type with head shapes of round plate and circular cone was selected in this study. The experimental variables were development length, number of bars, and head shape. Specimens were classified into L-type and S-type depending on the development length. The development length of L-type was computed according to the design code without considering the limit. S-type specimens had shorter development lengths than the L-type. Further classification was made depending on the shape of heads. A-types have the head shape of round plate and B-types have the shape of circular cone. Three L-type specimens were fabricated with the variable of number of bars (1, 2, and 3). Four specimens for each of SA and SB types were made with development lengths of 50%, 45%, 40%, and 35% compared with L-type. Pullout tests was carried out with 11 specimens. The test results were compared with computed strengths with the design code equations (Appendix II). Based the current studies, it can be said that high strength headed deformed bars used in this study be able to provide such strengths computed with the current design code without considering the yield strength limit.
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