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Title Derivation of Optimized Shape Equations for Ducts in Deviation Saddles
Authors 연정흠(Jung-Heum Yon)
DOI https://doi.org/10.4334/JKCI.2018.30.6.601
Page pp.601-608
ISSN 1229-5515
Keywords 프리스트레스트 콘크리트 ; 외부 긴장재 ; 방향변환블록 ; 덕트 ; 곡률마찰 prestressed concrete ; external tendon ; deviation saddle ; duct ; curvature friction
Abstract In externally prestressed concrete girders, a deviation saddle should be designed to support the deviation force when deviation saddle is attached to concrete section. The deviation saddle can be designed more effectively if the deviation force is uniformly distributed on a duct in the saddle. In this paper, equations of normal and deviation forces on the duct, in which the tendon force is decreased by curvature friction, have been derived. The optimized shape equation of the duct has been derived for curvature radius which satisfies the allowable deviation force in design codes for any tangent angle. Semi-major and semi-minor axes of an elliptic shape duct have been proposed. The elliptic shape duct shows behavior similar to those of the optimized shape duct. The efficiencies of the optimized and elliptic shape ducts have been proved by comparing size effects and distributions of deviation forces with those of a circular shape duct.