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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Computational Structural Engineering Institute of Korea
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Journal DOI :
The Computational Structural Engineering Institute
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Volume & Issues
Volume 20, Issue 6 - Dec 2007
Volume 20, Issue 5 - Oct 2007
Volume 20, Issue 4 - Aug 2007
Volume 20, Issue 3 - Jun 2007
Volume 20, Issue 2 - Apr 2007
Volume 20, Issue 1 - Feb 2007
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An Elastic Parabolic Cable Element for Initial Shaping Analysis of Cable-Stayed Bridges
Kyung, Yong-Soo ; Kim, Moon-Young ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 1~7
This study introduces an elastic parabolic cable element for initial shaping analysis of cable-stayed bridges. First, an elastic catenary cable theory is shortly summarized by deriving the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element. Next, the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived from the assumption that sag configuration under self-weights is small. In addition the equivalent cable tension is defined in the chord-wise direction. Finally, to confirm the accuracy of this element, initial shaping analysis of cable-stayed bridges under dead loads is executed using TCUD in which stay cables are modeled by an elastic parabolic cable and an elastic catenary cable element, respectively. Resultantly it turns that unstrained lengths of stay cables, the equivalent cable tensions, and maximum tensions by the parabolic cable element are nearly the same as those by the catenary cable elements.
Material Topology Optimization Design of Structures using SIMP Approach Part I : Initial Design Domain with Topology of Partial Holes
Lee, Dong-Kyu ; Park, Sung-Soo ; Shin, Soo-Mi ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 9~18
This study shows an implementation of partial holes in an initial design domain in order to improve convergences of topology optimization algorithms. The method is associated with a bubble method as introduced by Eschenauer et al. to overcome slow convergence of boundary-based shape optimization methods. However, contrary to the bubble method, initial holes are only implemented for initializations of optimization algorithm in this approach, and there is no need to consider a characteristic function which defines hole's deposition during every optimization procedure. In addition, solid and void regions within the initial design domain are not fixed but merged or split during optimization Procedures. Since this phenomenon activates finite changes of design parameters without numerically calculating movements and positions of holes, convergences of topology optimization algorithm can be improved. In the present study, material topology optimization designs of Michell-type beam utilizing the initial design domain with initial holes of varied sizes and shapes is carried out by using SIMP like a density distribution method. Numerical examples demonstrate the efficiency and simplicity of the present method.
Material Topology Optimization Design of Structures using SIMP Approach Part II : Initial Design Domain with Topology of Partial Solids
Lee, Dong-Kyu ; Park, Sung-Soo ; Shin, Soo-Mi ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 19~28
Discrete topology optimization processes of structures start from an initial design domain which is described by the topology of constant material densities. During optimization procedures, the structural topology changes in order to satisfy optimization problems in the fixed design domain, and finally, the optimization produces material density distributions with optimal topology. An introduction of initial holes in a design domain presented by Eschenauer et at. has been utilized in order to improve the optimization convergence of boundary-based shape optimization methods by generating finite changes of design variables. This means that an optimal topology depends on an initial topology with respect to topology optimization problems. In this study, it is investigated that various optimal topologies can be yielded under constraints of usable material, when partial solid phases are deposited in an initial design domain and thus initial topology is finitely changed. As a numerical application, structural topology optimization of a simple MBB-Beam is carried out, applying partial circular solid phases with varying sizes to an initial design domain.
Analysis of Anisotropic Folded Structures using Triangular and Quadrilateral Elements
Yoo, Yong-Min ; Yhim, Sung-Soon ; Chang, Suk-Yoon ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 29~37
This study deals with displacement analysis of anisotropic folded structures with triangular elements and quadrilateral elements. When folded plates are analyzed, triangular elements as well as quadrilateral elements are needed for conveniences of modelling. However, using triangular elements is not a simple problem. A simple formulation is presented which allows a quadrilateral element to degenerate into a triangular element. Therefore it can easily be used for computational simplicity and avoided complexities on mixed use of triangular element and quadrilateral element. In this paper, a high-order shear deformation theory using only Lagrangian interpolation functions and drilling degrees of freedom for folded plates are utilized for more accurate analysis. Especially, various results of anisotropic laminated and folded composite structures with triangular element and quadrilateral element show the structural behavior characteristics of them.
Cuboidal Infinite Elements for Soil-Structure-Interaction Analysis in Multi-Layered Half-Space
Seo, Choon-Gyo ; Yun, Chung-Bang ; Kim, Jae-Min ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 39~50
This paper presents 3D infinite elements for the elastodynamic problem with multi-layered half-space. Five different types of infinite elements are formulated by using approximate expressions of multiple wave components for the wave function in multi-layered soil media. They are horizontal, horizontal-corner, vortical, vertical-corner and vertical-horizontal-comer infinite elements. The elements can effectively be used for simulating wane radiation problems with multiple wave components. Numerical example analyses are presented for rigid disk, square footings and embedded footing on homogeneous and layered half-space. The numerical results show the effectiveness of the proposed infinite elements.
Parametric Study of K-Joint Offshore Structure
Jo, Chul-Hee ; Park, Kwan-Kyu ; Im, Sung-Woo ; Kim, Jun-Yong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 51~56
The K-joint is one of the commonly applied element in offshore structures. Due to its structural configuration, the stress concentration occurs in the joint. Considering the important effect to the structural safety and the design optimization, a design guideline is strongly required. The main variables determining the configuration of K-joint including
are closely investigated to find the individual effect to the Stress to K-joint. The maximum Stress of joint has been differed as per the variation of parameters. The parametric study has been numerically carried out and compare with the experimental data.
Transformation of Dynamic Loads into Equivalent Static Loads by the Selection Scheme of Primary Degrees of Freedom
Kim, Hyun-Gi ; Cho, Maeng-Hyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 57~63
The systematic method to construct equivalent static load from a given dynamic load is proposed in the present study. Previously reported works to construct equivalent static load were based on ad hoc methods. Due to improper selection of loading position, they may results in unreliable structural design. The present study proposes the employment of primary degrees of freedom for imposing the equivalent static loads. The degrees of freedom are selected by two-level condensation scheme with reliability and efficiency. In several numerical examples, the efficiency and reliability of the proposed scheme is verified by comparison displacement for equivalent static loading and dynamic loading at the critical time.
Structural System Identification by Iterative IRS
Baek, Sung-Min ; Kim, Hyun-Gi ; Kim, Ki-Ook ; Cho, Maeng-Hyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 65~73
In the inverse perturbation method, enormous computational resource was required to obtain reliable results, because all unspecified DOFs were considered as unknown variables. Thus, in the present study, a reduced system method is used to condense the unspecified DOFs by using the specified DOFs, and to improve the computational efficiency as well as the solution accuracy. In most of the conventional reduction methods, transformation errors occur in the transformation matrix between the unspecified DOFs and the specified DOFs. Thus it is hard to obtain reliable and accurate solution of inverse perturbation problems by reduction methods due to the error in the transformation matrix. This numerical trouble is resolved in the present study by adopting iterative improved reduced system(IIRS) as well as by updating the transformation matrix at every step. In this reduction method, system accuracy is related to the selection of the primary DOFs and Iteration time. And both are dependent to each other So, the two level condensation method (TLCS) is selected as Selection method of primary DOFs for increasing accuracy and reducing iteration time. Finally, numerical verification results of the present iterative inverse perturbation method (IIPM) are presented.
A Study on Shape Optimum Design for Stability of Elastic Structures
Yang, Wook-Jin ; Choi, Joo-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 75~82
This paper addresses a method for shape optimization of a continuous elastic body considering stability, i.e., buckling behavior. The sensitivity formula for critical load is analytically derived and expressed in terms of shape variation, based on the continuum formulation of the stability problem. Unlike the conventional finite difference method (FDM), this method is efficient in that only a couple of analyses are required regardless of the number of design parameters. Commercial software such as ANSYS can be employed since the method requires only the result of the analysis in computation of the sensitivity. Though the buckling problem is more efficiently solved by structural elements such as a beam and shell, elastic solids have been chosen for the buckling analysis because solid elements can generally be used for any kind of structure whether it is thick or thin. Sensitivity is then computed by using the mathematical package MATLAB with the initial stress and buckling analysis of ANSYS. Several problems we chosen in order to illustrate the efficiency of the presented method. They are applied to the shape optimization problems to minimize weight under allowed critical loads and to maximize critical loads under same volume.
Study on Hydroelastic Analysis of LNGC Cargo by Global-Local Analysis Technique
Park, Seong-Woo ; Cho, Jin-Rae ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 1, 2007, Pages 83~92
There are many numerical methods to solve large-scale fluid-structure interaction(FSI) problems. However, these methods require very fine mesh to achieve the reasonable numerical accuracy and stability due to the concentrated and volatile hydrodynamic pressure caused by the liquid sloshing. Consequently, the numerical analysis targeting for the long-period time response with the desired numerical accuracy Is very highly time-consuming. The aim of this paper is to suggest a new method to analyze the hydroelastic behavior of the LNGC containment by using the global-local numerical approach. The reliability of the presented method is firstly examined, and then its efficiency is demonstrated by presenting that the long-period local responses of the LNGC containment are obtained with relatively short CPU time.