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Title |
Study on Shear Performance of RC Beams with Web Openings Strengthened with Square and Octagonal-shaped-Reinforcements
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Authors |
김형국(Hyeong-Gook Kim) ; 이범식(Bum-Sik Lee) ; 정찬유(Chan-Yu Jung) ; 이정윤(Jung-Yoon Lee) ; 김길희(Kil-Hee Kim) |
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DOI |
https://doi.org/10.4334/JKCI.2020.32.6.513 |
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Keywords |
유공보; 유공보강근; 소성힌지; 전단성능; 균열제어 web opening system; web opening reinforcement; plastic hinge; shear performance; crack control |
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Abstract |
The application of web opening to RC beams causes problems in terms of the usability of structures due to the cracks and deflection of structural members in which stresses are concentrated around web openings. Conventional web opening reinforcing methods require additional reinforcement such as diagonal reinforcing bars for strengthening web openings. Difficulty in fixing the location of the diagonal reinforcing bars and low work-ability are pointed out as their disadvantages. Furthermore, because of inaccuracies in the design and prediction of the strength of RC members with web openings, it is common not to place web openings in the joints or plastic hinge regions of structures subjected to bending moment. In this study, a new web opening reinforcement was proposed, that has excellent work-ability and is efficient in strengthening the shear performance and controlling cracks of RC beams. To evaluate the effect of the proposed web opening reinforcement in improving the shear performance and controlling cracks in the plastic hinge regions of RC beams, loading tests were conducted with the shape and position of the reinforcement as variables. Test results showed that a specimen with the proposed web opening reinforcement has a shear performance equal to or higher than that of a specimen with existing bent-type web opening reinforcement. Moreover, all reinforcing bars constituting the proposed web opening reinforcement resist shear cracks in positive and negative drifts. When installing web opening in the plastic hinge region, it is possible to secure the required shear capacity of RC beams by reducing the diameter of web openings.
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