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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 18, Issue 4 - Dec 2005
Volume 18, Issue 3 - Sep 2005
Volume 18, Issue 2 - Jun 2005
Volume 18, Issue 1 - Mar 2005
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Design of Cylindrical Composite Shell for Optimal Dimensions
Chun Heong-Jae ; Park Hyuk-Sung ; Choi Yong-Jin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 219~226
In this study, the problem formulation and solution technique using genetic algorithms for design optimization of laminate composite cylindrical beam section are presented. The hollow cylindrical beams we usually used in the wheel chair. If the weight of wheel chair is reduced, it will lead to huge improvement in passenger's mobility and comfort. In this context, the replacement of steel by high performance and light weight composite material along with optimal design will be a good contribution in the process of weight reduction of a wheel chair. An artificial genetics approach for the design optimization of hollow cylindrical composite beam is presented. On applying the genetic algorithm, the optimal dimensions of hollow cylindrical composite beams which have equivalent rigidities to those of corresponding hollow cylindrical steel beams are obtained. Also structural analysis is conducted on the entire wheel chair structure incorporating Tsai-Wu failure criteria. The maximum Tsai-Wu failure criteria index is
which is moth less than value of 1.00 indicating no failure is observed under excessive loading condition. It is found that the substitution of steel by composite material could reduce the weight of wheel chair up to 45%.
Hybrid Control System Using On-Off Type LQG Algorithm
Jung Hyung-Jo ; Yoon Woo-Hyun ; Lee In-Won ; Park Kyu-Sik ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 227~243
This paper presents a hybrid control system combining lead rubber bearings and hydraulic actuators for seismic response control of a cable stayed bridge. Because multiple control devices are operating, a hybrid control system could improve the control performances. However, the overall system robustness may be impacted negatively by additional active control devices. Therefore, a secondary on-off type controller according to the responses of lead rubber bearings is combined with LQG algorithm to improve the controller robustness. Numerical simulation results show that control performances of the hybrid system controlled by an on off type LQG algorithm are improved compared to those of the passive and active control systems and are similar to those of performance oriented hybrid system controlled by a LQG algorithm with the similar peak and normed control forces. Furthermore, it is verified that the hybrid system with an on-off type LQG controller is more robust for stiffness matrix perturbation than conventional hybrid control of system, and there are no signs of instability in the overall system. The proposed control system also maintains the control performance under not only the design earthquakes but also the other earthquakes. Therefore, the hybrid control system using on-off type LQG algorithm could be proposed as an improved control strategy for seismically excited cable-stayed bridges containing many uncertainties.
Formulation on the Empirical Equation of the Cask Impact Forces by Dimensional Analysis
Kim Yong-Jae ; Choi Young-Jin ; Lee Young-Shin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 245~254
Radioactive material is used in the various fields. The numbers of transport for radioactive material have been gradually increased in both domestic and International regions. The safety of the cask should be secured to safely transport of radioactive material. The korean atomic law and the IAEA safety standards prescribe regulations lot the safe transport of radioactive material The cask for spent fuel is comprised of the body and the impact limiter. In this study, the empirical equation of the cask impact force is proposed based on the dimensional analysis. Using this empirical equation the characteristics of the impact limiter are analyzed. The results are also validated by comparing with the previous results of the impact area method and the finite element analysis. The present method can be used to predict the impact force of the cask.
A Boundary Method for Shape Design Sensitivity Analysis in Shape Optimization Problems and its Application
Kwak Hyun-Gu ; Choi Joo-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 255~263
This paper proposes an efficient boundary-based technique for the shape design sensitivity analysis in various disciplines. An analytical sensitivity formula in the form of a boundary integral is derived based on the continuum formulation for a general functional defined in the problems. The formula can be conveniently used for gradient computation in a variety of shape design problems. The advantage of using a boundary-based method is that the shape variation vectors are needed only on the boundary, not over the whole domain. The boundary shape variation vectors are conveniently computed by using finite. Perturbations of the shape geometry instead of complex analytical differentiation of the geometry functions. The potential flow problems and fillet problem are chosen to illustrate the efficiency of the proposed methodology.
A Numerical Study on the Static Strength of Tubular X-Joints With an Internal Ring Stiffener
Ryu Yeon-Sun ; Cho Hyun-Man ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 265~275
The objective of this paper is to numerically assess the behavior of tubular X-joints with an internal ing stiffener, and to evaluate the reinforcement effect of a ring stiffener, and to establish the strength formulae. Nonlinear finite element analysis is used to compute the static strength of axially loaded tubular joints. Numerical and experimental results are in good agreement for tubular X-joints. The chord lengths of simple and ring-stiffened X-joints are suggested to reduce chord end effect. And, internal ring stiffener is found to be efficient In improving static strength of tubular X-joints. Maximum strength ratios are calculated as
. Regression analyses are performed considering practical size of ring stiffener and strength estimation formulae for tubular X-joints with an internal ring stiffener are proposed.
Comparison of Limit Strength of Steel Cable-Stayed Bridges using Nonlinear Inelastic Displacement and Buckling Analyses
Kim Sung-Eock ; Choi Dong-Ho ; Ma Sang-Soo ; Song Weon-Keun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 277~289
The study examines the limit strength for steel cable-stayed bridges. A case studies have been performed in order to evaluate the limit strength lot steel cable-stayed bridges using nonlinear inelastic analysis approach and bifurcation point instability analysis approach, effective tangent modulus
method. To realize it, a practical nonlinear inelastic analysis condoling the initial shape is developed. In the initial shape analysis, updated structural configuration is introduced instead of initial member forces for beam-column members at every iterative step. Geometric and material nonlinearities of beam-column members are accounted by using stability function, and by using CRC tangent modulus and parabolic function, respectively Besides, geometric nonlinearity of cable members is accounted by using secant value of equivalent modulus of elasticity. The load-displacement relationships obtained by the proposed method are compared well with those given by other approaches. The limit strengths evaluated by the proposed nonlinear inelastic analysis for the proposed cable-stayed bridges with tee dimensional configuration compared with those by the inelastic bifurcation point instability analyses.
Probabilistic Behavior of In-plane Structure due to Multiple Correlated Uncertain Material Constants
Noh Hyuk-Chun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 291~302
Due to the importance of the parameter in structural response, the uncertain elastic modulus was located at the center of stochastic analysis, where the response variability caused by the uncertain system parameters is pursued. However when we analyze the so-called stochastic systems, as many parameters as possible must be included in the analysis if we want to obtain the response variability that can reach a true one, even in an approximate sense. In this paper, a formulation to determine the statistical behavior of in-plane structures due to multiple uncertain material parameters, i.e., elastic modulus and Poisson's ratio, is suggested. To this end, the polynomial expansion on the coefficients of constitutive matrix is employed. In constructing the modified auto-and cross-correlation functions, use is made of the general equation for n-th moment. For the computational purpose, the infinite series of stochastic sub-stiffness matrices is truncated preserving required accuracy. To demons4rate the validity of the proposed formulation, an exemplary example is analyzed and the results are compared with those obtained by means of classical Monte Carlo simulation, which is based on the local averaging scheme.
An Evaluation of Tensile Design Criteria of Cast-In-Place Anchor by Numerical Analysis
Suh Yong-Pyo ; Jang Jung-Bum ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 303~309
Numerical analysis is carried out to identify the appropriateness of the design codes that is available for the tensile design of fastening system at Nuclear Power Plant (NPP) in this study. This study is intended for the cast-in-place anchor that is widely used for the fastening of equipment in Korean NPPs. The microplane model and the elastic-perfectly plastic model are employed for the quasi-brittle material like concrete and for the ductile material like anchor bolt as constitutive model for numerical analysis and smeared crack model is employed to simulate the clack and damage phenomena. The developed numerical model is verified on a basis of the various test data of cast-in-place anchor. The appropriateness of both ACI 349 Code and CEB-FIP Code is evaluated for the tensile design of cast-in-place anchor and it is proved that both design codes give a conservative results for real tensile capacity of cast-in-place anchor.
Static and Dynamic Analysis of Plate Structures using a High Performance Finite Element
Han In-Seon ; Kim Sun-Hoon ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 311~320
In this paper an enhanced quadratic finite element for static and dynamic analysis of plate structures is presented. The performance of a proposed plate element is improved by the coupled use of non conforming displacement modes, the selective integration scheme, and the assumed shear strain fields. An efficient direct modification method is also applied to this element to solve the problem such as failure of the patch test due to the adoption of non conforming modes. The proposed quadratic finite element does not show any spurious mechanism and does not produce shear locking phenomena even with distorted meshes. It is shown that the results obtained by this element converged to analytical solutions very rapidly tough numerical tests for standard benchmark problems. It is also noted that this element is applicable to transient dynamic analysis of Mindlin plates.
Finite Element Formulation for Axisymmetric Linear Viscoelastic Problems
Oh Guen ; Sim Woo-Jin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 18, issue 3, 2005, Pages 321~332
In this paper, the time-domain finite element formulations for axisymmetric linear viscoelastic problems, especially for the viscoelastic hollow sphere and cylinder, under various boundary conditions are presented with the theoretical solutions of them obtained by using the elastic-viscoelastic correspondence principle. It is assumed that the viscoelastic material behaves like a standard linear solid in distortion and elastically in dilatation. Numerical examples are solved based on the spherically symmetric, axisymmetric and plane strain finite element models. Good agreements are obtained between numerical and theoretical solutions, which shows the validity and accuracy of the presented method.