• Title/Summary/Keyword: FBPier 3.0

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Application and Verification of Coupled Analysis of Piled Piers (교량 말뚝기초 해석기법의 적용성 분석)

  • Won Jin-Oh;Jeong Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.21 no.4
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    • pp.123-134
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    • 2005
  • A coupled three-dimensional pile group analysis method (YSGroup) was developed considering nonlinear pile head stiffness matrices and compared with other analytical methods (elastic displacement method, Group 6.0 and FBPier 3.0). In this method, a pile cap was modelled by four-node flat shell element, a pier was modelled using 3 dimensional beam element, and individual piles were modelled as beam-column elements. Through the comparative studies on a piled pie. subjected to lateral loads in linear soil, it was found that present method (YSGroup), elastic displacement method and Group 6.0 gave similar results of lateral pile head displacement, but FBPier 3.0 was estimated to show somewhat larger displacements than those from the three methods. Displacements of superstructure (pier), including nonlinear soil behavior, could be estimated by present method (YSGroup) and FBPier 3.0 because these two methods modelled the superstructure directly by finite element techniques. It was found that pile groups in pinned pile head condition had a tendency to cause excessive rotation of the pile cap.

Nonlinear Three-dimensional Analysis of Piled Piers Considering Coupled Cap Rigidities (교량 말뚝기초의 캡강성을 고려한 비선형 3차원 해석)

  • Won Jin-Oh;Jeong Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.21 no.6
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    • pp.19-30
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    • 2005
  • A coupled three-dimensional pile group analysis method was developed by considering complex behavior of sub-structures (pile-soil-cap) which included soil nonlinearity and the behavior of super-structure (pier). As an intermediate analysis method between FBPier 3.0 and Group 0.0, it took advantages of each method. Among the components of a pile group, individual piles were modeled with stiffness matrices of pile heads and soils with nonlinear load-transfer curves (t-z, q-z and p-y curves). A pile cap was modeled with modified four-node flat shell elements and a pier with three-dimensional beam element, so that a unified analysis could be possible. A nonlinear analysis method was proposed in this study with a mixed incremental and iteration techniques. The proposed method for a pile group subjected to axial and lateral loads was compared with othe. analytical methods (i.e., Group 6.0 and FBPier 3.0). It was found that the proposed method could predict the complex behavior of a pile group well, even though piles were modelled simply in this study by using pile head stiffness matrices which were different from the method introduced in FBPier 3.0.

Influence of Pile Cap's Boundary Conditions in Piled Pier Structures (교량 말뚝기초의 단부 지점조건의 영향분석)

  • Jeong, Sang-Seom;Won, Jin-Oh
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.25-32
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    • 2005
  • Modeling techniques of piled pier were reviewed and the influences of pile cap's boundary conditions were analyzed in this study. Among various modeling techniques, equivalent cantilever method seems relatively simple for modeling pile groups and it has some problems to determine the virtual fixed points. Through the analyses, it was found that the method of nonlinear p-y model with soil springs was more appropriate than equivalent cantilever method. The method modeling a pile group using stiffness matrix seems useful for practical design, which can represent the nonlinear three-dimensional behavior of a piled pier. In this study, the stiffness matrix of a pile group could be estimated efficiently and precisely using three-dimensional nonlinear analysis programs of pile groups (FBPier 3.0, YSGroup).

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A Study on the Optimum Design of Piled-raft Foundation Considering Pile Head Condition (말뚝두부구속조건을 고려한 말뚝지지 전면기초의 최적단면 설계)

  • Cho, Jae-Yeon;Lee, Sung-June;Jeong, Sang-Seom
    • Journal of the Korean Geotechnical Society
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    • v.26 no.12
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    • pp.31-40
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    • 2010
  • This study describes the three-dimensional behavior of pile foundations based on a numerical study. A series of numerical analyses were performed for connectivity conditions between piles and cap under vertical and lateral loadings. It is shown that a fixed connection between pile and cap is able to transfer significant bending moment through the connection and increases the pile lateral stiffness and the bending moment. Based on the results obtained, it was found that the cross sectional shear force in the raft with fixed head condition was larger than that of pinned head condition. Thus, the reinforcement of pile head and thickness of the raft also increases in fixed pile head condition. From the results, it is found that the overall behavior and cross sectional forces of pile foundations is affected significantly by the pile head conditions. Furthermore, the design of pile foundations with pinned head condition was judged to be less costly and very useful for preliminary design stages.