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Title |
Serviceability Check of Pretensioned Concrete Members Reinforced with 2,400 MPa High Strength Prestressing Strnads
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Authors |
주효은(Hyo-Eun Joo) ; 한선진(Sun-Jin Han) ; 주현진(Hyunjin Ju) ; 최승호(Seung-Ho Choi) ; 박민국(Min-Kook Park) ; 김강수(Kang Su Kim) |
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DOI |
https://doi.org/10.4334/JKCI.2018.30.1.075 |
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Keywords |
사용성 ; 2 ; 400 MPa 강연선 ; 프리스트레스트 콘크리트 ; 인장응력 ; 비선형 휨해석 serviceability ; 2 ; 400 MPa strands ; prestresssed concrete ; tensile stress ; non-linear analysis |
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Abstract |
In recent years, high strength 7-wire strands that have a 2,400 MPa tensile strength were developed, for which the serviceability check specified in ACI318-14 and KCI 2012 need to be reviewed. The current design codes (KCI 2012 or ACI318-14) permitted that the tensile stress of reinforcing bars at service loads can be assumed as two-thirds of their yield strengths. However, they restricted the net tensile stress of the prestressing strands in Class C prestressed concrete (PSC) members at service loads (Δfps) to be less than 250 MPa regardless of the tensile strengths of prestressing strands. Therefore, in this study, a parametric analysis was conducted on the PSC members reinforced with 2,400 MPa high strength prestressing strands considering the key influential factors on the Δfps, such as shape and size of section, partial prestressing ratio (PPR), reinforcing index (ω), and magnitude of effective prestress (fse). The analysis results showed that the Δfps is not affected by section size, and decreases in accordance with increasing fse, PPR, and cracking moment to service moment ratio (Mcr/Mservice). Based on the analysis results, a simple design table was suggested to check if the Δfps satisfies its limitation at the design stages, which does not require any complex iterative calculations for checking Δfps.
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