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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 17, Issue 4 - Dec 2004
Volume 17, Issue 3 - Sep 2004
Volume 17, Issue 2 - Jun 2004
Volume 17, Issue 1 - Mar 2004
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Control-Gain Estimation of Energy Dissipation Control Algorithms
Lee Sang Hyun ; Kang Sang Hoon ; Min Kyung-Won ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 343~350
This study is on control gain estimation of energy dissipation control algorithms. Velocity feedback saturated, bang bang, and energy gain control algorithms are proposed based on the Lyapunov stability theory and their performances are evaluated and compared. Saturation problem is considered in the design of the velocity feedback saturated and energy-gain control algorithms, and chattering problem in bang bang control is solved by using boundary layer. Numerical results show that the proposed control algorithms can dissipate the structural energy induced by wind loads efficiently.
Dynamic Stability Analysis of Nonconservative Systems for Variable Parameters using FE Method
Lee Jun-Seok ; Min Byoung-Cheol ; Kim Moon-Young ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 351~363
Equation of motion of non conservative system considering mass matrix, elastic stiffness matrix, load correction stiffness matrix by circulatory force's direction change and Winkler and Pasternak foundation stiffness matrix is derived. Also stability analysis due to the divergence and flutter loads is performed. And the influence of internal and external damping coefficient on flutter load is investigated applying the quadratic eigen problem solution. Additionally the influence of non-conservative force's direction parameter, internal and external damping and Winkler and Pasternak foundation on the critical load of Beck's and Leipholz's and Hauger's columns are investigated.
Analysis of Deformation and Stress Generated by Repair Welding and Its Accuracy
Chang Kyong-Ho ; Lee Sang-Hyong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 365~374
Steel bridges, which have been damaged by load and corrosion, need repair or strengthening. That is a cause of decreasing the durability of structure. In order to solve these problems, welding repair and strengthening methods can be considered. In general, cutting and welding procedure is carried out during the repair welding. Therefore, the investigation of the behavior of residual stress and deformation generated by cutting and welding is very important for safety of structure. Residual stress and deformation produced by gas cutting and arc welding were analyzed using 2D and 3D thermal elasto-plastic FEM. According to the results, the magnitude of temperature was analyzed by 2D-FEM is smaller than that was analyzed using the 3D-FEM at the start and end edge of flange. And the magnitude and distribution of residual stress of perpendicular direction of the cutting line and welding line was analyzed by the 2D-FEM was similar to that was analyzed by 3D-FEM. Therefore, it is possible to predict cutting and welding residual stress by 2D and 3D FEM.
Numerical Prediction of Ultimate Strength of RC Beams and Slabs with a Patch by p-Version Nonlinear Finite Element Modeling and Experimental Verification
Ahn Jae-Seok ; Park Jin-Hwan ; Woo Kwang-Sung ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 375~387
A new finite element model will be presented to analyze the nonlinear behavior of RC beams and slabs strengthened by a patch repair. The numerical approach is based on the p-version degenerate shell element including theory of anisotropic laminated composites, theory of materially and geometrically nonlinear plates. In the nonlinear formulation of this model, the total Lagrangian formulation is adopted with large deflections and moderate rotations being accounted for in the sense of von Karman hypothesis. The material model is based on hardening rule, crushing condition, plate-end debonding strength model and so on. The Gauss-Lobatto numerical quadrature is applied to calculate the stresses at the nodal points instead of Gauss points. The validity of the proposed p-version nonlinear finite element model is demonstrated through the load-deflection curves, the ultimate loads, and the failure modes of RC beams or slabs bonded with steel plates or FRP plates compared with available result of experiment and other numerical methods.
Modal based Structural Model Modification Using Genetic Algorithm
Yun Chung-Bang ; Lee Jong-Jae ; Lee Jung-Seok ; Juhn Gui-Hyun ; Yi Jin-Hak ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 389~403
This study presents the structural model modification based on the modal data such as natural frequencies and mode shapes. Preliminary structural model can be obtained using design drawings and field measurement, and therefore the deteriorated stiffness of a structure and the effect of the boundary conditions are difficult to be evaluated in preliminary analysis model, and the preliminary model can be modified using structural response data including static and/or dynamic characteristics. In this study, the structural model is modified based on the structural modal data using genetic algorithm. Modal testing were carried out for Imjin River Bridge and Hangjoo Bridge, the modal properties were estimated using modal identification techniques, and finally the structural models were updated using genetic algorithm. The modified structural model could give us more reliable structural analysis results and therefore those can be used for structural performance evaluation such as load carrying capacity and seismic capacity.
Temperature Analysis of the Cylindrical Structure with Multi-Holes of HANARO Irradiation Test
Choi Young-Jin ; Kang Young-Hwan ; Lee Young-Shin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 405~412
During the irradiation tests of material and fuel rod, all components of the cylindrical structure with multiple holes act like heat sources due to high gamma heat and fission heat. The objective of this study is to formulate the general solution for the temperature distribution to estimate the thermal integrity of structure during irradiation tests. For the temperature distribution analysis, the two-dimensional heat conduction theory is used. The unmerical analysis is performed by the commercial finite element analysis code, ANSYS 6.1. If the cylindrical structure with hole number would not exceed three holes, the analysis results and finite element results are good agreement together. For the structure with four holes, the discrepancy between FE results and analysis results of the structural temperature distribution is increased.
Creep Analysis for the Pressurized Water Reactor Spent Nuclear Fuel Disposal Canister
Ha Joon-Yong ; Choi Jong-Won ; Kwon Young-Joo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 413~421
In this paper, a structural analysis for the pressurized water reactor(PWR) spent nuclear fuel disposal canister which is deposited under the 500m deep underground is carried out to predict the creep deformation of the canister while the underground water and swelling bentonite pressure are applied on the canister. Usually the creep deformation may be caused due to the Pressure and the high heat applied to the canister even though additional external loads are not applied to the canister. These creep deformations depend on the time. In this paper, oかy the underground water and bentonite swelling Pressure are considered for the creep deformation analysis of the canister, because the heat distribution inside canister due the spent fuel is not simple and depends on time. A proper creep function is adopted for the creep analysis. The creep analysis is carried out during
seconds. The creep analysis results show that the creep strains are very small and these strains occur usually in the lid and bottom of the canister not in the cast iron insert. A much smaller strain is found in the cast iron insert. Hence, the creep deformation doesn't affect the structural safety of the canister, and also the creep stress which shows the stress relaxation phenomenon doesn't affect the structural safety of the canister
Fracture Mechanics Analysis of a Interface Crack in the Weld of Dissimilar Steels using the J-integral
Lee Chin-Hyung ; Chang Kyong-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 423~431
For the fracture mechanics analysis of cracks in welds of dissimilar steels, residual stress analysis and fracture analysis must be performed simultaneously. The standard definition of the J -integral leads to a path dependent value in the presence of a residual stress field. And unlike cracks in homogeneous materials, a bimaterial interface crack always induces both opening and shearing modes of stress in the vicinity of the crack tip. Therefore, it is necessary to develope a path independent J-integral definition for a crack in a residual stress field generated by welding of dissimilar steels. This paper addresses the modification of the Rice-J-integral to produce a path independent J -integral when residual stresses due to welding of dissimilar steels and external forces are present. The residual stress problem is treated as an initial strain problem and the J-integral proposed for this class of problems is used. And a program which can evaluate the J -integral for a crack in a weld of dissimialr steels is developed using proposed J integral definition.
Earthquake Response of Two Adjacent Buildings Founded at Different Depths
Lee Jong-Seh ; Yoon Soon-Jong ; Kim Dong-Woo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 433~442
The aim of this paper is to study the interaction between adjacent buildings with different foundation levels under earthquake loading conditions. Buildings and soil are represented by two different models. In the first case, the building itself is modeled with standard frame element, whereas the soil behavior is stimulated by a special grid model. In the second case, the building and soil are represented by plane stress or plane strain elements. The modulus of elasticity of the 9round as well as the varying relations of inertia have a strong influence on the section forces within the buildings. The Interaction between the two buildings is demonstrated and discussed via numerical examples using the proposed method.
Reliability Analysis of Steel Fiber Reinforced Concrete Continuous Beams
Yoo Han-Shin ; Jang Hwa-Sup ; Kwak Kae-Hwan ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 443~449
Methods for mixing variable types of steel fibers have been developed recently to suppress outbreak of crack or to control the width of crack and improve the load resistible capacity at the same time. On the other hand, uncertainty by complex nature of destruction dynamics of steel fiber reinforced concrete(SFRC) is included. In this study, analysis of reliance considering uncertainty of SFRC beam is done. For this, intensity limit state model was proposed. Moreover, characteristic values about almost every kinds of probability variables were collected and presented according to home and foreign references. Process of improving uncertainty from the result of experiments by Bayseian updating method is also proposed on the purpose of offering better statistical characteristic values with more data in the new future. Fatigue fracture probability equation is proposed and needed statistical characteristic values were presented to analyze fatigue reliance
Determination of the Frozen Penetration Depth of a Freezing Soil Medium including a Pipeline in a Closed System
Song Weon-Keun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 451~458
The study was focused on the development of computational scheme in three dimensional configurations by applying effective heat capacity model to the numerical procedure in order to predict the temperature profiles of a buried pipeline and the frozen penetration depth(FPD) of a freezing soil medium. To realize this, the investigator conducted the unsteady state heat transfer analysis, using the commercial code ABAQUS, for the freezing granite soil medium including a pipeline in a closed system. The proposed model took into consideration the phase change effect of in situ pore water in the frozen fringe. The comparison of results obtained by the proposed model and the actual performances was valuable in establishing a level of confidence in the application of introduced theory.
An Efficient Partial Reanalysis Algorithm for the Locally Changed Structures
Kim Chee-Kyeong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 17, issue 4, 2004, Pages 459~467
This paper presents an efficient reanalysis algorithm, named PRAS (Partial Reanalysis algorithm using Adaptable Substructuring), for the partially changed structures. The algorithm recalculates directly any displacement or member force under consideration in real time without a full reanalysis in spite of local changes in member stiffness or connectivity_ The key procedures consists of 1) partitioning the whole structure into the changed part and the unchanged part, 2) condensing the internal degrees of freedom and forming the unchanged part substructure, 3) assembling and solving the new stiffness matrix from the unchanged part substructure and the changed members.