• Title/Summary/Keyword: preloading of bracing

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Effects of Strut Preloading on the Restraining of Adjacent Ground Displacement at Braced Excavations (버팀 굴착시 버팀대 선행하중의 인접지반 변위 억제 효과)

  • 백규호;조현태
    • Journal of the Korean Geotechnical Society
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    • v.15 no.1
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    • pp.31-40
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    • 1999
  • The bracing system using screw jack is not effective for the restraining of adjacent ground displacement. since the screw jack dose not induce sufficient preloading on struts. In order to protect excessive displacement of adjacent ground at braced excavation, new preloading jack was developed in the country. In this paper, the new preloading jack and the measurement results of the lateral displacement of braced wall at three deep excavation sites in Seoul city are introduced. The measurement results showed that the maximum displacements of braced wall are smaller than 0.15% of excavation depth, therefore the wall displacements can be minimized by preloading which is acted on bracing. If the bracing system with new preloading jack is used in braced excavation, it is effective for reducing the cost and period of construction.

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Effect of Initial Uniform Moment on Lateral Free Vibration of Arches (등분포 모멘트를 받는 아치의 횡 자유진동)

  • 염응준;한택희;임남형;강영종
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.3-10
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    • 2002
  • Recently, arches are used structurally because of their high in-plane stiffness and strength, which result from their ability to transmit most of the applied loading by axial forces actions, so that the bending actions are reduced. On the other hand, the resistances of arches to (out-of-plane,) flexural-torsional behavior depend on the rigidities EI/sub y/, for lateral bending, GJ for Uniform torsion, and EI/sub w/ for warping torsion which are related to axial stress for flexural-torsional behavior. The resistance of an arch to out-of-plane behavior may be reduced by its in-plane curvature, and so it may require significant lateral bracing. Thus. it is supposed that In-plane preloading which cause an axial stress, have an effect on out-of-plane free vibration behavior of arches. Because axial stresses caused increase or decrease out-of-plane stiffness. But study about this substance is insufficient. In this thesis, We will study an effect of preloading on lateral free vibration of arches, using finite element method based on Kang and Yoo's curved beam theory (about curved beam element have 7 degree of freedom including warping) with FORTRAN programming.

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