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Title |
Reevaluation of the Design Equation for Development Length of Tension Reinforcement at Beam Ends
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Authors |
박상아(Sang-Ah Park) ; 김승훈(Seung-Hun Kim) ; 정재원(Jae-Won Jeong) |
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DOI |
https://doi.org/10.11112/jksmi.2026.30.1.99 |
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Keywords |
철근콘크리트; 보 단부; 고강도철근; 철근의 정착길이; 스트럿-타이 모델 Reinforced concrete; Beam end; High strength steel; Development length; Strut-tie model |
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Abstract |
This study reevaluates the design equations for the development length of tension reinforcement anchored at reinforced concrete beam ends subjected to bearing stress. Previous studies have shown that the current KDS 14 20 52 provisions are overly conservative when applied to beam-end anchorage in deep beams evaluated using strut-and-tie models (STMs). A total of 241 reinforced concrete deep beam specimens with shear span-to-depth ratios not exceeding 2.0 were collected from existing studies and classified according to the presence of vertical shear reinforcement. Appropriate strut-and-tie models were applied depending on the reinforcement configuration, and the anchorage capacity of tension ties was evaluated using development length equations from KDS and ACI codes. Comparisons between experimental and nominal shear strengths indicated that tension tie failure governed all specimens and that both codes significantly underestimated shear strength. The average ratios of experimental to nominal shear strength were 2.40 for KDS and 2.18 for ACI, confirming the conservative nature of the current provisions. The results demonstrate the need to reevaluate development length design equations for beam-end anchorage in conjunction with rational strut-and-tie model selection.
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