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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 29, Issue 4 - Aug 2016
Volume 29, Issue 3 - Jun 2016
Volume 29, Issue 2 - Apr 2016
Volume 29, Issue 1 - Feb 2016
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Structural Safety Assessment of a Concrete-filled Base Frame Supporting a Motor for Centrifugal Compressor Drives
Kim, Min-Jin ; Lee, Jae-Hoon ; Han, Jeong-Sam ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 1~8
DOI : 10.7734/COSEIK.2016.29.1.1
In this paper, we perform structural analysis for a base frame which is used to support a motor for large centrifugal compressor drives and a safety assessment according to the concrete placement. First, the structural analysis about four loading conditions for the motor base frame was conducted and the structural safety was evaluated through both the maximum distortion energy theory and Mohr-Coulomb theory. It was possible to perform a more reasonable safety evaluation against local stresses occurring at the discontinuous portion of the fragile structural members by applying the safety assessment through ASME VIII Div. 2. In addition, the motor base frames with and without the internal concrete placement were quantitatively compared by the structural analysis and safety evaluation using ASME code and it was found to improve the structural integrity due to the concrete placement.
Numerical Analysis of Vortex Induced Vibration of Circular Cylinder in Lock-in Regime
Lee, Sungsu ; Hwang, Kyu-Kwan ; Son, Hyun-A ; Jung, Dong-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 9~18
DOI : 10.7734/COSEIK.2016.29.1.9
The slender structures such as high rise building or marine riser are highly susceptible to dynamic force exerted by fluid-structure interactions among which vortex-induced vibration(VIV) is the main cause of dynamic unstability of the structural system. If VIV occurs in natural frequency regime of the structure, fatigue failure likely happens by so-called lock-in phenomenon. This study presents the numerical analysis of dynamic behavior of both structure and fluid in the lock-in regimes and investigates the subjacent phenomena to hold the resonance frequency in spite of the change of flow condition. Unsteady and laminar flow was considered for a two-dimensional circular cylinder which was assumed to move freely in 1 degree of freedom in the direction orthogonal to the uniform inflow. Fluid-structure interaction was implemented by solving both unsteady flow and dynamic motion of the structure sequentially in each time step where the fluid domain was remeshed considering the movement of the body. The results show reasonable agreements with previous studies and reveal characteristic features of the lock-in phenomena. Not only the lift force but also drag force are drastically increasing during the lock-in regime, the vertical displacement of the cylinder reaches up to 20% of the diameter of the cylinder. The correlation analysis between lift and vertical displacement clearly show the dramatic change of the phase difference from in-phase to out-of-phase when the cylinder experiences lock-in. From the results, it can be postulated that the change of phase difference and flow condition is responsible for the resonating behavior of the structure during lock-in.
Comparison of Super Structure-Sub Structure Separation Analysis and Unification Analysis about Building Structures
Kim, Jae-Yo ; Kim, Jin-Yong ; Kang, Su-Min ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 19~28
DOI : 10.7734/COSEIK.2016.29.1.19
In the case of structural analysis for building structures, the super-structure and the sub-structure are analyzed by using separate structural models in the field because of time saving, facile result interpretation and easy analysis of dynamic behavior. However this separate structural model violated the compatibility condition of structural analysis and it can not consider the interaction of superand sub- structures. In the present study, the analysis results of this separate model were compared to those of the unified model of super- and sub- structures which can consider the interaction of super- and sub- structures and reflect the realistic boundary conditions. According to the comparison results, the the analysis model using separate models can underestimate the member force and deflection of structural members in the super-structures and overestimate the deflection and member force of sub-structures. Therefore, in the case of high-rise buildings, irregular shaped buildings, buildings which are expected to be affected by large differential settlement and remodeling buildings, the unified structural model for super- and sub- structures was recommended for structural analysis instead of the separate structural model.
On the Design of Lifting Lugs Based on the Ultimate Strength
Lee, Joo-Sung ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 29~36
DOI : 10.7734/COSEIK.2016.29.1.29
Lifting lugs are frequently used to transport and to turn over blocks of ship and offshore structures in a shipyard. As the shipbuilding technology has been developed, blocks has become bigger and bigger, and block management technology takes a more important role in shipbuilding to enhance the productivity. For the sake of economy as well as safety in design of lug structure, needed is a more rational design procedure based on the ultimate strength derived through the rigorous non-linear structural analysis considering both the material and geometric non-linearity. This study is aimed at deriving the optimum design of T type lug structure which is frequently used in a shipyard. The optimum thickness of lug's main body is to be determined based on the results of non-linear strength analysis. As far as the present results for T type lugs having various capacity are concerned, it can be said that the present optimum design result can guarantee both safety and economy. From the fact that any regular trend cannot be found in weight reduction to the capacity of lugs, it seems to be necessary to review the current design procedure of lug structure. The present design procedure can be extensively used in design of various types of lug structures used in shipyard.
Dynamic Response Analysis of 2.5MW Wind Turbine Gearbox with Flexible Pins
Cho, Jin-Rae ; Jeong, Ki-Yong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 37~44
DOI : 10.7734/COSEIK.2016.29.1.37
This study is concerned with the numerical investigation of dynamic characteristics of 2.5MW-class wind turbine gearbox in which the misalignment improvement of plenary gear shafts by the flexible pins and the dynamic impact response are analyzed by the finite element method. The tooth contact between gears is modelled using the line element having the equivalent tooth stiffness and the contact ratio to accurately and effectively reflect the load transmission in the internal complex gear system. The equivalent tooth stiffness is calculated by utilizing the tooth deformation analysis and the impulse torque is applied to the input shaft for the dynamics response characteristic analysis. Through the numerical experiments, the equivalent tooth stiffness model was validated and the misalignment improvement of planetary gear shafts was confirmed from the comparison with the cases of fixed shafts at one and both ends.
Analysis of Bicycle Cushion System by using Repulsive Force of Magnetics
Yun, Seong-Ho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 45~52
DOI : 10.7734/COSEIK.2016.29.1.45
One commercial package for magnetic analysis was used to apply repulsive forces of permanent magnetics to bicycle cushion system. Reliabilities of finite element analysis were acquired by comparing with those of experimental measurements. Equivalent spring stiffnesses corresponding to various sizes of magnetics were implemented into the bicycle dynamic model with three degree of freedom. Input force caused at front and rear wheels due to road unevenness was considered in the dynamic model. Dynamic behaviors were observed in terms of vertical displacements of the rider and the front reach as well as pitching displacement of the mass center when the bicycle ran over half-triangular bump. The methodology suggested in this paper by the finite element analysis and numerical model will be an useful tool for more accurate prediction of cushion design for any vehicle system if magnetic forces are utilized.
Comparative Study on the Thermal Insulation of Membrane LNG CCS by Heat Transfer Analysis
Hwang, Se-Yun ; Lee, Jang-Hyun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 53~60
DOI : 10.7734/COSEIK.2016.29.1.53
This study discusses the thermal insulation capacity of variant of NO96 LNG (liquefied natural gas) cargo containment insulation system. Changing the insulation materials and the insulation layers of conventional GTT NO96 containment system, The thermal resistance and BOR(boil off rate) caused by the heat transfer between cryogenic and environmental temperature is discussed. Therefore, thermal analysis of LNG CCS(cargo containment system) is carried out to determine the insulation capabilities. Also, BOR is evaluated in terms of the total amount of heat invaded into CCS(cargo containment system). Variant of NO96 CCS such as NO96, NO96GW and NO96L3 membrane type during laden voyage is selected for the comparative study. Finite element model for heat transfer analysis is conducted by employing the equivalent thermal resistance model to simplify the complex insulation layers. Finally the results for each variant model are relatively compared and discussed to minimize the BOR.
Study on Material Properties of Composite Materials using Finite Element Method
Jung, Chul-Gyun ; Kim, Sung-Uk ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 61~65
DOI : 10.7734/COSEIK.2016.29.1.61
Composites are materials that are widely used in industries such as automobile and aircraft. The composite material is required as a material for using in a high temperature environment as well as acting as a high pressure environment like the nozzle part of the ship. It is important to know the properties of composites. Result values obtained substituting the properties of matrix and fiber numerically have an large error compared with experimental value. In this study we utilize CASADsolver EDISON program for using Finite Element Method. Properties by substituting the fiber and Matrix properties of the composite material properties were compared with those measured in the experiment and calculated by the empirical properties.
A Suggestion of Simplified Load Formula for Blast Analysis
Jeon, Doo-Jin ; Han, Sang-Eul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 67~75
DOI : 10.7734/COSEIK.2016.29.1.67
In this paper, a pressure-time history curve of blast load and Conwep model are presented, and a simplified blast load formula is suggested. Generally, a blast load are applied as a pressure-time history curve, and it is calculated by blast load formula such as Conwep model. The Conwep model which is used in most of the blast analysis is quiet difficult to calculate because of its complex process. Therefore, a simplified formula is proposed to calculate blast load by simple rational expressions and to make a simplified pressure-time history curve. In this process, a curve fitting method was used to find the simple rational expressions. The calculation results of the simplified formula have an error of less than 1% in comparison with the Conwep model. And, blast analyses using finite elements method are accomplished with the Conwep model and simplified formula for verification.
A Study on Pipe Spool considering Workspace based on Genetic Algorithm
Yu, Seong-Sang ; Lee, Kyung-Ho ; Lee, Jung-Min ; Nam, Byeong-Wook ; Kim, Hyun ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 77~83
DOI : 10.7734/COSEIK.2016.29.1.77
Pipe working is consist of design, making and installation. Pipe line is consist of spool pipes which are made in fabrication shop. And these spool pipes installation in shipyard. Spool pipes are designed based 2D Drawings(ISO Drawing), so spool pipes are not considered working area, that wake decreasing working efficiency and delay working time. In this paper, suggest make spool pipe design method using analysis working area about 3D CAD model and genetic algorithm.
Finite Element Analysis of Reinforced Concrete Masonry Infilled Frames with Different Masonry Wall Thickness Subjected to In-plane Loading
Kim, Chungman ; Yu, Eunjong ; Kim, Minjae ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 85~93
DOI : 10.7734/COSEIK.2016.29.1.85
In this study, finite element analyses of masonry infilled frames using a general purpose FE program, ABAQUS, were conducted. Analysis models consisted of the bare frame, infilled frames with masonry wall thickness of 0.5B and 1.0B, respectively. The masonry walls were constructed using the concrete bricks which were generally used in Korea as infilled wall. The material properties of frames and masonry for the analysis were obtained from material tests. However, four times increased the tensile strength was used for 1.0B wall, which is seemingly due to the differences in locating the bricks. The force-displacement relation and development of crack from the FE analysis were very similar to those from the experiments. From the FEA results, contact force between the frame and masonry, distribution of shear force and bending moments in frame members were analyzed. Obtained contact stress shows a trianglur distribution, and the contact length for 0.5B speciment and 1.0B specimen were close to the value estimated using ASCE 41-06 equation and ASCE 41-13 equation, respectively. Obtained shear force and bending moment distribution seems to replicate actual behavior which originates from the contact stress and gap between the frame and masonry.
A Study on Aerodynamic Damping and Aeroelastic Instability of Helical-shaped Super Tall Building
Kim, Wonsul ; Yoshida, Akihito ; Tamura, Yukio ; Yi, Jin-Hak ;
Journal of the Computational Structural Engineering Institute of Korea, volume 29, issue 1, 2016, Pages 95~103
DOI : 10.7734/COSEIK.2016.29.1.95
In this paper, aeroelastic instability and aerodynamic damping ratio of a helical
model which shows better aerodynamic behavior in both along-wind and crosswind responses on a super tall building was investigated by an aeroelastic model test, and the aerodynamic damping ratio was evaluated from the wind-induced responses of the model by using Random Decrement Technique. Aerodynamic damping ratios evaluated in this study were verified through comparison with previous results obtained by quasi-steady theory. As a result, the aeroelastic instability of the helical
model in crosswind direction were not occurred for any conditions with increasing the reduced wind velocity while the square model generally encounters aeroinstability due to the vortex shedding. The aerodynamic damping in along-wind direction for the helical
and the square model increased monotonically both with reduced wind velocity, i.e., there is no relation with modifications of building shapes. On the other hand, in crosswind direction, the characteristics of aerodynamic damping ratio with reduced wind velocity for helical
model were quit different from those of the square model.