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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 21, Issue 6 - Dec 2008
Volume 21, Issue 5 - Oct 2008
Volume 21, Issue 4 - Aug 2008
Volume 21, Issue 3 - Jun 2008
Volume 21, Issue 2 - Apr 2008
Volume 21, Issue 1 - Feb 2008
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Damage Detection in Shear Building Based on Genetic Algorithm Using Flexibility Matrix
Na, Chae-Kuk ; Kim, Sun-Pil ; Kwak, Hyo-Gyoung ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 1~11
Stiffness estimation of a shear building due to local damages is usually achieved though structural analysis based on the assumed material properties and idealized numerical modeling of structure. Conventional numerical modeling, however, frequently causes an inevitable error in the structural response and this makes it difficult to exactly predict the damage state in structure. To solve this problem, this paper introduces a damage detection technique for shear building using genetic algorithm. The introduced algorithm evaluates the damage in structure using a flexibility matrix since the flexibility matrix can exactly be obtained from the field test in spite of using a few lower dynamic modes of structure. The introduced algorithm is expected to be more effectively used in damage detection of structures rather than conventional method using the stiffness matrix. Moreover, even in cases when an accurate measurement of structural stiffness cannot be expected, the proposed technique makes it possible to estimate the absolute change in stiffness of the structure on the basis of genetic algorithm. The validity of the proposed technique is demonstrated though numerical analysis using OPENSEES.
Numerical Analysis for the Characteristic Investigation of Homogenization Techniques Used for Equivalent Material Properties of Functionally Graded Material
Cho, Jin-Rae ; Choi, Joo-Hyoung ; Shin, Dae-Sub ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 13~20
Graded layers in which two different constituent particles are mixed are inserted into functionally graded material such that the volume fractions of constituent particles vary continuously and functionally over the entire material domain. The material properties of this dual-phase graded region, which is essential for the numerical analysis of the thermo-mechanical behavior of FGM, have been predicted by traditional homogenization methods. But, these methods are limited to predict the global equivalent material properties of FGMs because the detailed geometry information such as the particel shape and the dispersion structure is not considered. In this context, this study intends to investigate the characteristics of these homogenization methods through the finite element analysis utilizing the discrete micromechanics models of the graded layer, for various volume fractions and external loading conditions.
Integrated Genetic Algorithm with Direct Search for Optimum Design of RC Frames
Kwak, Hyo-Gyoung ; Kim, Ji-Eun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 21~34
An improved optimum design method for reinforced concrete frames using integrated genetic algorithm(GA) with direct search method is presented. First, various sets of initially assumed sections are generated using GA, and then, for each resultant design member force condition optimum solutions are selected by regression analysis and direct search within pre-determined design section database. In advance, global optimum solutions are selected from accumulated results through several generations. Proposed algorithm makes up for the weak point in standard genetic algorithm(GA), that is, low efficiency in convergence causing the deterioration of quality of final solutions and shows fast convergence together with improved results. Moreover, for the purpose of elevating economic efficiency, optimum design based on the nonlinear structural analysis is performed and therefore makes all members resist against given loading condition with the nearest resisting capacity. The investigation for the effectiveness of the introduced design procedure is conducted through correlation study for example structures.
A Study on the Thermo-Mechanical Fatigue Loading for Time Reduction in Fabricating an Artificial Cracked Specimen
Lee, Gyu-Beom ; Choi, Joo-Ho ; An, Dae-Hwan ; Lee, Bo-Young ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 35~42
In the nuclear power plant, early detection of fatigue crack by non-destructive test (NDT) equipment due to the thermal cyclic load is very important in terms of strict safety regulation. To this end, many efforts are exerted to the fabrication of artificial cracked specimen for practicing engineers in the NDT company. The crack of this kind, however, cannot be made by conventional machining, but should be made under thermal cyclic load that is close to the in-situ condition, which takes tremendous time due to the repetition. In this study, thermal loading condition is investigated to minimize the time for fabricating the cracked specimen using simulation technique which predicts the crack initiation and propagation behavior. Simulation and experiment are conducted under an initial assumed condition for validation purpose. A number of simulations are conducted next under a variety of heating and cooling conditions, from which the best solution to achieve minimum time for crack with wanted size is found. In the simulation, general purpose software ANSYS is used for the stress analysis, MATLAB is used to compute crack initiation life, and ZENCRACK, which is special purpose software for crack growth prediction, is used to compute crack propagation life. As a result of the study, the time for the crack to reach the size of 1mm is predicted from the 418 hours at the initial condition to the 319 hours at the optimum condition, which is about 24% reduction.
Flexural Behavior of Steel Composite Beam with Built-up Cross-section Considering Bolt Deformation
Kim, Sung-Bo ; Kim, Hun-Kyom ; Jung, Kyoung-Hwan ; Han, Man-Yop ; Kim, Moon-Young ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 43~50
The analysis and results of flexural behavior for steel composite beam with built-up cross-section considering bolt deformation are presented in this paper. The bolt deformation and the restrict effect due to bolt-connection and friction are considered to investigate the flexural behavior of steel composite beam. Nonlinear spring element in ABAQUS is used to consider bolt deformation, also the results are compared with those in case bolt deformations are ignored. The displacement, bending stresses and shear stresses are calculated by F.E. model, and these results are compared with the analytical value of no interaction beam, partial interaction beam and full interaction beam. As a result of analysis, the behavior of composite beam is more dependant on the composite rate than the friction of the steel. When the composite rate is more than 50%, the behavior of composite beam considering the effects of bolt deformation is similar to that of fully composite beam.
A Micromechanics based Elastic Constitutive Model for Particle-Reinforced Composites Containing Weakened Interfaces and Microcracks
Lee, Haeng-Ki ; Pyo, Suk-Hoon ; Kim, Hyeong-Ki ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 51~58
A constitutive model based on a combination of a micromechanics-based weakened interface elastic model (Lee and Pyo, 2007) and a crack nucleation model (Karihaloo and Fu, 1989) is proposed to predict the effective elastic behavior of particle-reinforced composites. The model specifically considers imperfect interfaces in particles and microcracks in the matrix. To exercise the proposed constitutive model and to investigate the influence of model parameters on the behavior of the composites, numerical simulations on uniaxial tension tests were conducted. Furthermore, the present prediction is compared with available experimental data in the literature to verify the accuracy of the proposed constitutive model.
Distributed Hybrid Simulation and Testing System using General-Purpose Finite Element Analysis Program
Yun, Gun-Jin ; Han, Bong-Koo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 59~71
In this paper, a software framework that integrates computational and experimental simulation has been developed to simulate and test a large-scale structural system under earthquake loading. The proposed software framework does not need development of the computer codes for both dynamic and static simulations. Any general-purpose software can be utilized with a main control module and interface APIs. This opens up a new opportunity to facilitate use of sophisticated finite elements into hybrid simulation regime to enhance accuracy and efficiency of simulations. The software framework described in the paper is modular and uses object oriented programming concepts. A series of illustrative examples demonstrate that the system is fully-functional and is capable of running any number of experimental and/or analytical components.
Regularization Method by Subset Selection for Structural Damage Detection
Yun, Gun-Jin ; Han, Bong-Koo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 73~82
In this paper, a new regularization method by parameter subset selection method is proposed based on the residual force vector for damage localization. Although subset selection using the fundamental modal characteristics as a residual function has been successful in detecting a single damage location, this method seems to have limited capabilities in the detection of multiple damage locations and typically requires cumbersome weighting values. The method is presented herein and considers cases in which damage detection must be achieved using incomplete measurements of the structural responses. Model expansion is incorporated to deal with this challenge. The unique advantage of employing the new regularization method is that it can reliably identify multiple damage locations. Through an illustrative example, the proposed damage detection method is demonstrated to be a reliable tool for identifying multiple damage locations for a planar truss structure.
Vibration-Based Monitoring of Prestress-Loss in PSC Girder Bridges
Kim, Jeong-Tae ; Hong, Dong-Soo ; Park, Jae-Hyung ; Cho, Hyun-Man ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 83~90
A vibration-based monitoring system is newly proposed to predict the loss of prestress forces in prestressed concrete (PSC) girder bridges. Firstly, a global damage alarming algorithm is newly proposed to monitor the occurrence of prestress-loss by using the change in frequency responses. Secondly, a prestress-loss prediction algorithm is selected to estimate the extent of prestress-loss by using the change in natural frequencies. Finally, the feasibility of the proposed system is experimentally evaluated on a scaled PSC girder model for which acceleration responses were measured for several damage scenarios of prestress-loss.
Structural Analysis Models to Develop Live Load Distribution Factors of Simply Supported Prestressed Concrete I-Girder Bridge
Lee, Hwan-Woo ; Kim, Kwang-Yang ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 91~101
Structural analysis models to develop live load distribution factors of simply supported prestressed concrete I-girder bridge should have the precision of the analysis results as well as modeling simplicity. This is due to the numerous frequency of structural analysis needed while developing live load distribution factors. In this study, an appropriate structural analysis model is selected by comparing previous researchs studies and models used in practical design. Also, the influence by the flexural stiffness of barrier and diaphragm on the live load distribution had been analyzed through comparing the numerical analysis and experimental tests. As a result, the model that the eccentric girder and the barrier and diaphragm are connected to the deck plate was appropriate in satisfying both accuracy and simplicity for structural analysis of simply supported prestressed concrete I-girder bridge. However, the barrier was analyzed to have insignificant influence on the live load distribution in spite of its variation of stiffness. The eccentric diaphragm showed little influence at 25% or higher of flexural stiffness. From the results, a model that the girder is rigidly connected to the deck plate in consideration of the eccentricity, the barrier is ignored and the whole section of diaphragm is supposed to be valid without eccentricity is decided as the most appropriate structural model to develop the live load distribution factors of simply supported prestressed concrete I-girder bridge in this study.
Determination of the Thickness of RC Shear Wall Outriggers
Lee, Jae-Cheol ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 103~111
The purpose of this study is to find the way to determine the thickness of RC shear wall outriggers of tall buildings. For this, the analysis models of tall buildings with 60 stories are generated and analyzed. Then the changes of load transfer and deformation caused by the outriggers are investigated and the equation for the determination of the thickness of RC shear wall outriggers is proposed. Finally, the proposed equation is verified for the variously modified analysis models.
Integrated Structural Design Operation by Process Decomposition and Parallelization
Hwang, Jin-Ha ; Park, Jong-Hoi ;
Journal of the Computational Structural Engineering Institute of Korea, volume 21, issue 1, 2008, Pages 113~124
Distributed operation of overall structural design process, by which product optimization and process parallelization are simultaneously implemented, is presented in this paper. The database-interacted hybrid method, which selectively takes the accustomed procedure of the conventional method in the framework of the optimal design, is utilized here. The staged application of design constraints reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes are simultaneously implemented by concurrent engineering approach in the distributed environment of PC networks. The former is based on finite element optimization method and the latter is represented by AutoCAD using AutoLISP programming language. Numerical computation and database interaction on servers and graphic works on independent clients are communicated through message passing. The numerical experiments for some steel truss models show the validity and usability of the method. This study has sufficient adaptability and expandability, in that it is based on general methodologies and industry standard platforms.