• Title, Summary, Keyword: 상대 절점 변위

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A Relative Nodal Displacement Method for Element Nonlinear Analysis (상대 절점 변위를 이용한 비선형 유한 요소 해석법)

  • Kim Wan Goo;Bae Dae sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.4
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    • pp.534-539
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    • 2005
  • Nodal displacements are referred to the initial configuration in the total Lagrangian formulation and to the last converged configuration in the updated Lagrangian furmulation. This research proposes a relative nodal displacement method to represent the position and orientation for a node in truss structures. Since the proposed method measures the relative nodal displacements relative to its adjacent nodal reference frame, they are still small for a truss structure undergoing large deformations for the small size elements. As a consequence, element formulations developed under the small deformation assumption are still valid for structures undergoing large deformations, which significantly simplifies the equations of equilibrium. A structural system is represented by a graph to systematically develop the governing equations of equilibrium for general systems. A node and an element are represented by a node and an edge in graph representation, respectively. Closed loops are opened to form a spanning tree by cutting edges. Two computational sequences are defined in the graph representation. One is the forward path sequence that is used to recover the Cartesian nodal displacements from relative nodal displacement sand traverses a graph from the base node towards the terminal nodes. The other is the backward path sequence that is used to recover the nodal forces in the relative coordinate system from the known nodal forces in the absolute coordinate system and traverses from the terminal nodes towards the base node. One open loop and one closed loop structure undergoing large deformations are analyzed to demonstrate the efficiency and validity of the proposed method.

Non-Prismatic Beam Element for Beams with RBS Connection (RBS 연결부를 갖는 보에 대한 부등 단면 보 요소)

  • Kim, Kee Dong;Ko, Man Gi;Hwang, Byoung Kuk;Pae, Chang Kyu
    • Journal of Korean Society of Steel Construction
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    • v.16 no.6
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    • pp.833-846
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    • 2004
  • This study presents a non-prismatic beam element for modeling the elastic behavior of steel beams, which have the post-Northridge connections in steel moment frames. The elastic stiffness matrix, including the shear effects for non-prismatic members with reduced beam section (RBS) connection, is in closed form. A simplified approach is also suggested, which uses a prismatic beam element to model beams with the RBS connection. This method can estimate quiteexactly the maximum story drift ratios of frames with the RBS connection. The effects of reduced beam section connection on the elastic stiffness of steel moment frames were investigated. The selection of a proper model to account for deformations at the joint might have a more important role in estimating the maximum story drift ratios of frames with better accuracy than the RBS cutouts.

A Relative for Finite Element Nonlinear Structural Analysis (상대절점좌표를 이용한 비선형 유한요소해석법)

  • Kang, Ki-Rang;Cho, Heui-Je;Bae, Dae-Sung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.788-791
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    • 2005
  • Nodal displacements are referred to the Initial configuration in the total Lagrangian formulation and to the last converged configuration in the updated Lagrangian formulation. This research proposes a relative nodal displacement method to represent the position and orientation for a node in truss structures. Since the proposed method measures the relative nodal displacements relative to its adjacent nodal reference frame, they are still small for a truss structure undergoing large deformations for the small size elements. As a consequence, element formulations developed under the small deformation assumption are still valid fer structures undergoing large deformations, which significantly simplifies the equations of equilibrium. A structural system is represented by a graph to systematically develop the governing equations of equilibrium for general systems. A node and an element are represented by a node and an edge in graph representation, respectively. Closed loops are opened to form a spanning tree by cutting edges. Two computational sequences are defined in the graph representation. One is the forward path sequence that is used to recover the Cartesian nodal displacements from relative nodal displacements and traverses a graph from the base node towards the terminal nodes. The other is the backward path sequence that is used to recover the nodal forces in the relative coordinate system from the known nodal forces in the absolute coordinate system and traverses from the terminal nodes towards the base node. One closed loop structure undergoing large deformations is analyzed to demonstrate the efficiency and validity of the proposed method.

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Evaluation of the Stress Intensity Factor for a Crack in Bimaterial Plate by the Boundary Method (경계요소법에 의한 이종재료내 크랙의 응력확대계수 평가)

  • Kim, Sang-Cheol;Im, Won-Gyun
    • Journal of the Korean Society for Precision Engineering
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    • v.9 no.2
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    • pp.108-115
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    • 1992
  • 이종재료의 접합면에 수직으로 존재하는 크랙에 대하여 경계요소 해석을 수행하여, 그 결과 실용가능한 수치 근사해을 얻을 수 있었다. 크랙을 정확히 모델링하기 위하여 크랙표면을 분리영역으로 하는 영역분할법을 채택하였으며, 해의 정확성을 향상시키기 위하여 등매개 2차요소로의 경계분할과 함께 크랙선단에서 표면력의 특이성을 나타내도록 하였다. 응력확대계수는 크랙표면상 절점의 상대변위를 이용하여 결정하였다. 또한 이종 재료내 크랙에 대하여 응력확대계수를 간단히 구할 수 있는 간편해석법을 제안하고 이의 적용 가능한 범위를 제 시하였다.

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Experimental Study on the Inelastic Behavior of Single-layer Latticed Dome with New Connection (새로운 접합상세를 가진 단층 래티스 돔의 비탄성 거동에 관한 실험연구)

  • Kim, Myeong Han;Oh, Myoung Ho;Jung, Seong Yeol;Kim, Sang Dae
    • Journal of Korean Society of Steel Construction
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    • v.21 no.2
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    • pp.145-154
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    • 2009
  • This study discusses the inelastic behavior of single-layer latticed dome, which consists of a tubular truss member and newly proposed joint sections, through a loading test on a scaled-down structure. The loading test was performed under displacement control conditions, using loading transfer system for the same value of point loads on all joints. The maximum applied load was nearly 1.6 times of the design load, and structural failure occurred after exceeding the compressive yielding in some members. Structural displacement was maintained up to the limit of the oil jack. The behavior of the latticed dome from the loading test was analyzed according to the order of loading steps.

Behavior of Back Ground of the Laterally Loaded Single Pile (수평하중이 작용하는 단독말뚝의 배면지반의 저항거동 특성)

  • Bae, Jong-Soon;Kim, Sung-Ho
    • Journal of the Korean Geotechnical Society
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    • v.24 no.8
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    • pp.53-60
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    • 2008
  • In this study, various kinds of behavior characteristics such as deformation area zone of back ground, failure angle and rotation point are examined on the laterally loaded single pile in the homogeneous ground through a model test. The main obtained conclusions are summarized as follows; In the back ground of single pile to which the lateral load is applied, failure surface shows almost linear movement characteristics and it is inclined to converge to constant values no matter how the length of pile and the pile head displacement.

Experimental Study on the Inelastic Behavior of Single-layer Latticed Dome (단층 래티스 돔의 비탄성 거동에 대한 실험연구)

  • Kim, Jong-Soo;Kim, Sang-Dae;Kim, Myeong-Han;Oh, Myoung-Ho;Shin, Chang-Hoon
    • Proceeding of KASS Symposium
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    • pp.165-170
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    • 2008
  • This study discusses the inelastic behavior of single-layer latticed dome, composed of tubular truss member and newly proposed joint sections, through loading test on the scale-down structure. The loading test was performed under displacement control conditions, using loading transfer system for the same value of point loads on all joints. Maximum applied load was nearly 1.6 times of the design load, and inelastic buckling occured beyond compressive yeilding in some members. The displacement of structure was maimtained upto the limit of oil jack. The behavior of latticed dome from the loading test was analyzed on the view of structural design practice.

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