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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
Journal Basic Information
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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Topology Optimization of Actuator for Thermo-Elastic Systems
Lim, O-Kaung ; Kim, Dae-Woo ; Choi, Eun-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 683~690
Topology optimization techniques have been developed as a very efficient design tool and utilized for design engineering processes in many industrial sections during the past decade. And topology optimization has become the focus into structural optimization design up to now. Recently, thermally actuated compliant mechanisms have a wide range of applications. In this research, the thermo-elastic problem is a coupled problem which has to consider heat transfer analysis and structural analysis. Hence, the thermo-elastic problem has to deal with heat transfer material properties and structural material properties at the same time. The numerical examples are presented. From the results, it was shown that in terms of the displacement after optimization. Moreover, this paper compared thermo-system, elastic-system with thermo-elastic system and was shown a good result of topology optimization while thermo-elastic system was used.
Finite Element Eigen Analysis of Undamped Beam Structure with Composite Sections
Park, Keun-Man ; Cho, Jin-Rae ; Jung, Weui-Bong ; Bae, Soo-Ryong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 691~697
Numerical eigen analysis of beam-like structure can be easily and effectively done by various conventional beam theory-based methods. However, in case of the structures composed of composite-sectioned beams, the application of conventional numerical methods requires one to derive both equivalent material and geometry properties. In the present paper, these equivalent properties are derived by the transformed section method and the test FEM program is coded. The numerical accuracy of the proposed method is verified through the comparison with the ANSYS 3-D model.
Effect of Reinforcement for Web Opening on Shear Strength of Reinforced Concrete Deep Beams
Lee, Jong-Kweon ; Choi, Yun-Cheul ; Lee, Yong-Taeg ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 699~708
Reinforced concrete deep beams are general structural members used as transfer-girder, pile cap, foundation wall and so on. They have a complex stess formation. Generally, failure mechanisms differ from either continuous deep beams or simple supported deep beams. In continuous deep beams, a negative moment is occurred over intermediate support and the location of maximum moment coincide with high shear force. Therefore, failure usually occurs at this region. While on the other hand, in simple supported deep beam, the region of high shear coincides with the region of low moment. The web opening of deep beams for accepting a facility makes shear behaviors of deep beams more complex and gives rise to an expansion of crack around the opening and a decline of shear capacity of deep beams. Therefore, Engineers must determine a delicate reinforcement method to control a crack and increase a shear capacity. The purpose of this report is a computation of an effective reinforcement method through non-linear finite element method by means of adopting various reinforcement method as variables and a computation of shear capacity formula taking an effectiveness of reinforcement into consideration.
Effect of an Intermediate Support on the Stability of a Beam resting on Elastic Foundation Subjected to Follower Force
Kim, Jae-On ; Lee, Kee-Seok ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 709~717
This paper discussed on the effect of an intermediate support on the stability of a beam resting on elastic foundation subjected to follower force. The stability and dynamic responses of a beam resting on elastic foundation subjected to follower force are analyzed based on the finite element method. The dynamic responses of the system are studied by the mode superposition method to observe the damping rate of the motion. The beam resting on elastic foundation subjected to follower force loses its stability by flutter type or divergence type, depending on the location of the intermediate support.
An Assumed Strain Beam Element for Spatial Post-Buckling Analysis of Non-symmetric and Shear Flexible Thin-Walled Beams
Lee, Kyoung-Chan ; Kim, Moon-Young ; Park, Jung-Il ; Chang, Sung-Pil ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 719~730
This study presents a thin-walled space frame element based on the classical Timoshenko beam theory. The element is derived according to the assumed strain field in order to resolve the shear-locking phenomenon. The shape function is developed in accordance with the strain field which is assumed to be constant at a 2-noded straight frame element. In this study, the geometrically nonlinear analysis applies the Corotational procedure in order to evaluate unbalanced loads. The bowing effect is also considered faithfully. Two numerical examples are given; monosymmetric curved and nonsymmetric straight cantilever. When these example structures behave lateral-torsional bucking, the critical loads are obtained by this study and ABAQUS shell elements. Also, the post-buckling behavior is examined. The results give good agreement between this study and ABAQUS shell.
New Nonlinear Analysis Algorithm Using Equivalent Load for Stiffness
Kim, Yeong-Min ; Kim, Chee-Kyeong ; Kim, Tae-Jin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 731~742
This paper presents a new nonlinear analysis algorithm, that is, adaptive Newton-Raphson iteration method, The presented algorithm is based on the existing Newton-Raphson method, and the concept of it can be summarized as calculating the equivalent load for stiffness(ELS) and adapting this to the initial global stiffness matrix which has already been calculated and saved in initial analysis and finally calculating the correction displacements for the nonlinear analysis, The key characteristics of the proposed algorithm is that it calculates the inverse matrix of the global stiffness matrix only once irresponsive of the number of load steps. The efficiency of the proposed algorithm depends on the ratio of the active Dofs - the Dofs which are directly connected to the members of which the element stiffness are changed - to the total Dofs, and based on this ratio by using the proposed algorithm as a complementary method to the existing algorithm the efficiency of the nonlinear analysis can be improved dramatically.
Interior Eigenvalue Computation Using Algebraic Substructuring
Ko, Jin-Hwan ; Byun, Do-Young ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 743~749
Algebraic substructuring (AS) is a state-of-the-art method in eigenvalue computations, especially for large size problems, but, originally, it was designed to calculate only the smallest eigenvalues. In this paper, an updated version of AS is proposed to calculate the interior eigenvalues over a specified range by using a shift value, which is referred to as the shifted AS. Numerical experiments demonstrate that the proposed method has better efficiency to compute numerous interior eigenvalues for the finite element models of structural problems than a Lanczos-type method.
Optimal Active-Control & Development of Optimization Algorithm for Reduction of Drag in Flow Problems(3) -Construction of the Formulation for True Newton Method and Application to Viscous Drag Reduction of Three-Dimensional Flow
Bark, Jai-Hyeong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 751~759
We have developed several methods for the optimization problem having large-scale and highly nonlinear system. First, step by step method in optimization process was employed to improve the convergence. In addition, techniques of furnishing good initial guesses for analysis using sensitivity information acquired from optimization iteration, and of manipulating analysis/optimization convergency criterion motivated from simultaneous technique were used. We applied them to flow control problem and verified their efficiency and robustness. However, they are based on quasi-Newton method that approximate the Hessian matrix using exact first derivatives. However solution of the Navier-Stokes equations are very cost, so we want to improve the efficiency of the optimization algorithm as much as possible. Thus we develop a true Newton method that uses exact Hessian matrix. And we apply that to the three-dimensional problem of flow around a sphere. This problem is certainly intractable with existing methods for optimal flow control. However, we can attack such problems with the methods that we developed previously and true Newton method.
Seismic Response Control of Structures Using Decentralized Response-Dependent MR Dampers
Youn, Kyung-Jo ; Min, Kyung-Won ; Lee, Sang-Hyun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 761~767
In centralized control system, complicated control systems including sensors, power supply and dampers should be required to satisfy the target response of large-scale structures. The practical applications of the centralized control system, however, is very difficult due to high order finite element model of structures, uncertainty of models, and limitations of the excitation system. In this study, the decentralized response-dependent MR damper of which magnetic field is automatically modulated according to the displacement or velocity transferred to the damper without any sensing and computing systems. this decentralized response-dependent MR damper are investigated according to the ranges of relative magnitude between the control force of MR damper and the story shear force of structures by nonlinear time history analysis. Finally, its performance is compared with centralized LQR algorithm which is used in general centralized control theory for a three story building structure.
Design of an Excitation System for Simulating Wind-Induced Response and Evaluating Wind-load Resistance Characteristics
Park, Eun-Churn ; Lee, Sung-Kyung ; Min, Kyung-Won ; Chun, Lan ; Kang, Kyung-Soo ; Lee, Sang-Hyun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 769~778
In this paper, excitation systems using linear mass shaker (LMS) and active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop function are used such that the error between the wind and actuator induced responses is minimized by preventing the actuator from exciting unexpected modal response and initial transient response. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.
Heat Transfer Analysis of Bi-Material Problem with Interfacial Boundary Using Moving Least Squares Finite Difference Method
Yoon, Young-Cheol ; Kim, Do-Wan ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 779~787
This paper presents a highly efficient moving least squares finite difference method (MLS FDM) for a heat transfer problem of bi-material with interfacial boundary. The MLS FDM directly discretizes governing differential equations based on a node set without a grid structure. In the method, difference equations are constructed by the Taylor polynomial expanded by moving least squares method. The wedge function is designed on the concept of hyperplane function and is embedded in the derivative approximation formula on the moving least squares sense. Thus interfacial singular behavior like normal derivative jump is naturally modeled and the merit of MLS FDM in fast derivative computation is assured. Numerical experiments for heat transfer problem of bi-material with different heat conductivities show that the developed method achieves high efficiency as well as good accuracy in interface problems.
A Formulation for Response Variability of Plates Considering Multiple Random Parameters
Noh, Hyuk-Chun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 20, issue 6, 2007, Pages 789~799
In this paper, we propose a stochastic finite element formulation which takes into account the randonmess in the material and geometrical parameters. The formulation is proposed for plate structures, and is based on the weighted integral approach. Contrary to the case of elastic modulus, plate thickness contributes to the stiffness as a third-order function. Furthermore, Poisson's ratio is even more complex since this parameter appears in the constitutive relations in the fraction form. Accordingly, we employ Taylor's expansion to derive decomposed stochastic field functions in ascending order. In order to verify the proposed formulation, the results obtained using the proposed scheme are compared with those in the literature and those of Monte Carlo analysis as well.