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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 22, Issue 6 - Dec 2009
Volume 22, Issue 5 - Oct 2009
Volume 22, Issue 4 - Aug 2009
Volume 22, Issue 3 - Jun 2009
Volume 22, Issue 2 - Apr 2009
Volume 22, Issue 1 - Feb 2009
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Reliability-based Design Optimization using Multiplicative Decomposition Method
Kim, Tae-Kyun ; Lee, Tae-Hee ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 299~306
Design optimization is a method to find optimum point which minimizes the objective function while satisfying design constraints. The conventional optimization does not consider the uncertainty originated from modeling or manufacturing process, so optimum point often locates on the boundaries of constraints. Reliability based design optimization includes optimization technique and reliability analysis that calculates the reliability of the system. Reliability analysis can be classified into simulation method, fast probability integration method, and moment-based reliability method. In most generally used MPP based reliability analysis, which is one of fast probability integration method, if many MPP points exist, cost and numerical error can increase in the process of transforming constraints into standard normal distribution space. In this paper, multiplicative decomposition method is used as a reliability analysis for RBDO, and sensitivity analysis is performed to apply gradient based optimization algorithm. To illustrate whole process of RBDO mathematical and engineering examples are illustrated.
A Bifurcation Analysis of Space Structures by Using 3D Beam-Column Element Considering Finite Deformations and Bowing Effect
Lee, Kyung-Soo ; Han, Sang-Eul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 307~314
The present paper briefly describes the space frame element and the fundamental strategies in computational elastic bifurcation theory of geometrically nonlinear, single load parameter conservative elastic spatial structures. A method for large deformation(rotation) analysis of space frame is based on an eulerian formulation, which takes into consideration the effects of large joint translations and rotations with finite deformation(rotation). The local member force-deformation relationships are based on the beam-column approach, and the change in member chord lengths caused by axial strain and flexural bowing are taken into account. and the derived geometric stiffness matrix is unsymmetric because of the fact that finite rotations are not commutative under addition. To detect the singular point such as bifurcation point, an iterative pin-pointing algorithm is proposed. And the path switching mode for bifurcation path is based on the non-negative eigen-value and it's corresponding eigen-vector. Some numerical examples for bifurcation analysis are carried out for a plane frame, plane circular arch and space dome structures are described.
Analysis of Moving Boundary Problem Using Extended Moving Least Squares Finite Difference Method
Yoon, Young-Cheol ; Kim, Do-Wan ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 315~322
This paper presents a novel numerical method based on the extended moving least squares finite difference method(MLS FDM) for solving 1-D Stefan problem. The MLS FDM is employed for easy numerical modelling of the moving boundary and Taylor polynomial is extended using wedge function for accurate capturing of interfacial singularity. Difference equations for the governing equations are constructed by implicit method which makes the numerical method stable. Numerical experiments prove that the extended MLS FDM show high accuracy and efficiency in solving semi-infinite melting, cylindrical solidification problems with moving interfacial boundary.
A Methodology for Automatic Hierarchy Definition of Sentences in Engineering Documents
Park, Sang-Il ; Kim, Bong-Geun ; Kim, Kyeong-Hwan ; Lee, Sang-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 323~330
This paper proposes a methodology for automatic hierarchy classification of subtitles in a engineering document by the a fact that heading symbols of subtitles represent a hierarchical structure of the document. The proposed methodology is composed of two methods: extracting subtitles from plan text document and determining hierarchical structure of the subtitles. The subtitles in a document is extracted by comparing heading symbol patterns with predefined heading symbol groups, and the depth levels of the subtitles are determined by analyzing relative location of subtitles according to change of the heading symbol patterns. A prototype module, which can transform a plain text document into a structured XML document in accordance with a hierarchical structure of subtitles, is developed based on the proposed methodology, and the performance of the module is analyzed with 20 engineering documents.
A Study of Surface Stress Effects on Equilibrium States of thin Nanofilm
Kim, Won-Bae ; Cho, Maeng-Hyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 331~334
In this paper, we present a surface relaxation model in atomistic calculations for thin nanofilms. This surface relaxation model is very simple model which have only two degrees of freedoms to determine the atomic positions of nanofilms. Whereas in conventional molecular statics simulations, the same number of degrees of freedoms at all atom positions are used as unknown variables. In order to prove the reliability of the presented model, we present the results of self-equilibrium strain calculations with the surface parameters obtained from this model.
MLS-Based Finite Elements and a Proposal for Their Applications
Cho, Young-Sam ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 335~341
In this paper, review of developed MLS-based finite elements and a proposal for their applications are described. The shape functions and their derivatives of MLS-based finite elements are constructed using Moving-Least Square approximation. In MLS-based finite element, using the adequate influence domain of weight function used in MLS approximation, kronecker delta condition could be satisfied at the element boundary. Moreover, because of the characteristics of MLS approximation, we could easily add extra nodes at an arbitrary position in MLS-based finite elements. For these reasons, until now, several variable-node elements(2D variable element for linear case and quadratic case and 3D variable-node elements) and finite crack elements are developed using MLS-based finite elements concept. MLS-based finite elements could be extended to 2D variable-node triangle element, 2D finite crack triangle element, variable-node shell element, finite crack shell element, and 3D polyhedron element. In this paper, we showed the feasibility of 3D polyhedron element at the case of femur meshing.
A Study on the Development of Multiscale Bridging Method Considering the Particle Size and Concentration Effect of Nanocomposites
Yang, Seung-Hwa ; Yu, Su-Young ; Cho, Maeng-Hyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 343~348
In this study, an efficient sequential bridging method to characterize both the particle size effect and concentration effect on the mechanical properties of nanocomposites at high volume fraction is suggested through a molecular dynamics(MD) simulations and micromechanics of composites materials. The Young's modulus and the shear modulus of the nanocomposites at various particle radius and at 12% volume fraction were obtained from MD simulations and multi-inclusion model was adopted to describe both modulus in continuum model. In order to describe the particle size effect, an additional phase, effective interface, was adopted as characteristic phase and the non-dilute concentration effect which appears at 12% volume fraction was describe via the variation of the elastic modulus of the infinite medium. Both the elastic modulus of the interface and infinite medium were fitted into functions of particle radius for the applicability of the present bridging method at various particle radii. Using the present bridging method the elastic modulus of the nanocomposites was efficiently obtained with accuracy. In addition, the effect of the interface thickness and modulus on the elastic modulus of the nanocomposite was investigated.
Selection of Sensing Members in a High-rise Building Structures using Displacement Participation Factors and Strain Energy Density
Lee, Hong-Min ; Park, Sung-Woo ; Park, Hyo-Seon ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 349~354
To rationally secure and maintain the safety and serviceability of a high-rise building, monitoring of structural responses of members is necessary. As such health monitoring of large-scale building structures has received growing attention by researchers in recent years. However, due to a very large number of members complexity of structural responses of a high-rise building structure, practical difficulties exist in selection of structural members to be sensored for assessment of structural safety of a structure. In this paper, a selection technique for active members for safety monitoring of a high-rise building based on displacement participation factor and strain energy density of a member is investigated.
Fragility Analysis of RC Moment Resisting Frame with Masonry Infill Walls
Ko, Hyun ; Park, Yong-Koo ; Lee, Dong-Guen ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 355~362
Many of residential buildings, which have pilotis in lower stories to meet the architectural needs, are recently constructed in Korea. Usually, infill walls located in the upper stories of these buildings may cause a soft first story, which is very weak from the earthquake resistance. In the design of the buildings, the infill walls of upper stories are usually considered as non-structural elements and thus they are not included in the analytical model. However, the infill walls may affect the seismic behavior of the residential buildings. Therefore, the differences in seismic behaviors of RC buildings with and without masonry infill walls are required to be investigated. In this study, seismic fragility analyses were performed for masonry infilled low-rise RC moment-resisting frames. And seismic behaviors of RC moment-resisting frame with/without masonry infill walls were evaluated. Two types of structural system with the same frame and different allocation of infill walls are used to evaluate the influence of masonry infill walls on seismic behavior of RC moment-resisting frames. The infill walls were modeled as bi-equivalent diagonal struts. The fragility analyses show that the seismic performance of RC moment-resisting frames with soft story is below the desirable building seismic performance level recommended by current seismic codes, indicating high vulnerability of RC moment-resisting frames with soft story.
Large Deformation Inelastic Analysis of API-X80 Steel Linepipes
Lee, Seung-Jung ; Yoon, Young-Cheol ; Cho, Woo-Yeon ; Yu, Seong-Mun ; Zi,, Goang-Seup ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 363~370
We simulated large deformation and inelastic behavior of API-X80 steel linepipes using nonlinear finite element method. Gurson-Tvergaard-Needleman(GTN) model is employed for the development of the constitutive model of the steel. The GTN model is implemented in the form of the user-supplied material subroutine(UMAT) for the commercial software of ABAQUS. To calibrate the model parameters, we simulated the behavior of the uniaxial tension test using ABAQUS equipped with the developed GTN model. Using the set of the model parameters, we were able to capture the characteristics of the plastic buckling of API-X80 steel linepipes.
Theoretical Investigation of 2DOF Vibrating System and Its Application to Dynamic Vibration Absorber
Jang, Seon-Jun ; Brennan, M.J. ; Rustigh, E. ; Jung, Hyung-Jo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 22, issue 4, 2009, Pages 371~377
In this paper, the dynamic characteristic of vibrating system which has translational and rotational degrees of freedom is studied. The moment of inertia of the system is modeled here as the inerter and the equivalent model to the system is proposed using dynamic stiffness method. It is shown that the size of inerter plays a major role to determine the dynamic characteristic of the system. This two degree of freedom system(DOF) is applied as a dynamic vibration absorber(DVA) to the elimination of single peak of main body. The solution for the undamped DVA is presented in analytical form while the damped DVA is designed using fixed point theory. The numerical examples are presented for verifying the methods.