• Title/Summary/Keyword: U형보

Search Result 3, Processing Time 0.015 seconds

Optimization for the Least Weight, Precast Prestressed Gerber′s U-Beams (최소자중 프리캐스트 프리스트레스트 게르버 U형보의 최적화)

  • 박현석;김인규;유승룡
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.3
    • /
    • pp.373-381
    • /
    • 2002
  • The cost on transmission and erection of the precast prestressed concrete members largely depends on the weight of them. Optimum process is performed on a U-beam section to control the prestressing force, to reduce the self-weight, and to meet the required strength and stability. The strength, deflection, and concrete stress at the top and bottom of the section considered are required to check according to each construction step in this process. The weight of the original rectangular concrete beam could be reduced up to 39∼50% from this method. Two full scale prototype U-beams were proposed and tested in this study. It was found that the U-beams in the test showed good performance in strength and serviceability within the limits of ultimate strength design method.

Optimization for Precast Prestressed Wide-U Beams with the Least Depth (최소깊이 프리캐스트 프리스트레스트 U형보의 최적화)

  • Yul Sung-Yong
    • Journal of the Korea Concrete Institute
    • /
    • v.16 no.1 s.79
    • /
    • pp.18-26
    • /
    • 2004
  • The cost of underground work is a dominant factor to determine the total construction fee. It is generally 2 ${\~}$ 2.5 times higher than that of above ground for building with the same height. 'A new precast prestressed framing plan for underground parking building' was suggested with the beam of the least depth - U-type beams. The depth of regular rectangular reinforced concrete beam which is currently used in the underground parking of apartments could be reduced up to 12 ${\~}$ 34cm/story due to the development of a U-beams from the optimum process. Two full scale prototype U-beams were tested in this study. It was found that the Wide U-beams in the test showed higher strength than calculated nominal and design, however need to provide temporary supports to meet the flexural moment of construction load at the simply supported state before the lopping concrete hardens.

Evaluation on Shear Performance of the Dapped Ends of Precast Gerber′s U-Beams (프리캐스트 게르버 U형보의 댑 전단 거동평가)

  • 박현석;유승룡
    • Journal of the Korea Concrete Institute
    • /
    • v.14 no.4
    • /
    • pp.492-502
    • /
    • 2002
  • The dapped ends of the Gerber's beam were designed by PCI(Prestressed Concrete Institute) and CPCI(Canadian Prestressed Concrete Institute) methods. The depths of nibs with precast and topping concrete, which were halves of the total beam depth, were 77 cm md 18.2 cm, respectably. Shear tests were performed on four full scale beam ends. All specimens designed by PCI and CPCI methods showed crackings at the re-entrant coner of dap before the 32 % of full service design loading, and failed at the load level higher than their design strength but less than their calculated nominal strength. The specimens with increased hanger reinforcement show more effective in development of initial crackings, more ductile in failure with distributed crackings, and failed in higher strength than those of PCI requirement. The tested specimens designed by CPCI method were more ductile in failure than those of the PCI methods.