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Title |
Prediction of Curvature Ductility of Doubly Reinforced Concrete Beams based on Tensile Strain of Reinforcement
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Authors |
이대형(Dae-Hyoung Lee) ; 배수호(Su-Ho Bae) |
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DOI |
https://doi.org/10.4334/JKCI.2026.38.5.601 |
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Keywords |
복철근 휨부재; 곡률연성도; 인장변형률/항복변형률 비; 압축철근비 doubly reinforced flexural member; curvature ductility; tensile-to-yield strain ratio; compressive reinforcement ratio |
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Abstract |
This study proposes a practical equation for predicting the curvature ductility of doubly reinforced concrete flexural members. Nonlinear analysis of the moment?curvature relationship was performed using concrete compressive strength, steel yield strength, and tension/compression reinforcement ratios as the primary variables, and the influence of the ratio of tensile strain to yield strain on curvature ductility was systematically investigated. The results indicate that curvature ductility improves as the ratio of tensile strain to yield strain increases. Conversely, when equal amounts of reinforcement are added to both the tension and compression sides, the increased member stiffness raises the yield curvature, thereby reducing the curvature ductility. The proposed equation, which employs the ratio of tensile strain to yield strain as a single predictor variable, accurately estimates curvature ductility with a coefficient of determination (R²) of 0.9 or higher and a mean relative error within 2%. These results demonstrate that the proposed equation can be practically applied to the evaluation and design of ductile reinforced concrete flexural members within a performance-based design framework.
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