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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 27, Issue 6 - Dec 2014
Volume 27, Issue 5 - Oct 2014
Volume 27, Issue 4 - Aug 2014
Volume 27, Issue 3 - Jun 2014
Volume 27, Issue 2 - Apr 2014
Volume 27, Issue 1 - Feb 2014
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Shape Design Optimization of Crack Propagation Problems Using Meshfree Methods
Kim, Jae-Hyun ; Ha, Seung-Hyun ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 337~343
DOI : 10.7734/COSEIK.2014.27.5.337
This paper presents a continuum-based shape design sensitivity analysis(DSA) method for crack propagation problems using a reproducing kernel method(RKM), which facilitates the remeshing problem required for finite element analysis(FEA) and provides the higher order shape functions by increasing the continuity of the kernel functions. A linear elasticity is considered to obtain the required stress field around the crack tip for the evaluation of J-integral. The sensitivity of displacement field and stress intensity factor(SIF) with respect to shape design variables are derived using a material derivative approach. For efficient computation of design sensitivity, an adjoint variable method is employed tather than the direct differentiation method. Through numerical examples, The mesh-free and the DSA methods show excellent agreement with finite difference results. The DSA results are further extended to a shape optimization of crack propagation problems to control the propagation path.
Experimental Validation of Isogeometric Optimal Design
Choi, Myung-Jin ; Yoon, Min-Ho ; Cho, Seonho ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 345~352
DOI : 10.7734/COSEIK.2014.27.5.345
In this paper, the CAD data for the optimal shape design obtained by isogeometric shape optimization is directly used to fabricate the specimen by using 3D printer for the experimental validation. In a conventional finite element method, the geometric approximation inherent in the mesh leads to the accuracy issue in response analysis and design sensitivity analysis. Furthermore, in the finite element based shape optimization, subsequent communication with CAD description is required in the design optimization process, which results in the loss of optimal design information during the communication. Isogeometric analysis method employs the same NURBS basis functions and control points used in CAD systems, which enables to use exact geometrical properties like normal vector and curvature information in the response analysis and design sensitivity analysis procedure. Also, it vastly simplify the design modification of complex geometries without communicating with the CAD description of geometry during design optimization process. Therefore, the information of optimal design and material volume is exactly reflected to fabricate the specimen for experimental validation. Through the design optimization examples of elasticity problem, it is experimentally shown that the optimal design has higher stiffness than the initial design. Also, the experimental results match very well with the numerical results. Using a non-contact optical 3D deformation measuring system for strain distribution, it is shown that the stress concentration is significantly alleviated in the optimal design compared with the initial design.
Thickness Measure and Characteristic Length for Effective Young's Modulus of Model Ice Plate in the Ice Basin
Lee, Jae-Hwan ; Choi, Bong-Kyun ; Lee, Chun-Ju ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 353~360
DOI : 10.7734/COSEIK.2014.27.5.353
The model ice is created at KRISO (Korea Research Institute for Ships and Ocean Engineering) ice basin where model ship is tested to obtain the necessary data in order to design the ice breaking vessels and ocean structures operating in the northern pole sea area. Through the model ship test, ice breaking, clearing, ice-ship and ice-propeller interaction behavior can be obtained. Since mechanical properties of ice plate are required for the model test, some tests are performed to obtain the properties in this paper. First, ultrasonic devide is used to measure the thickness of the model ice plate and the results show the possibility of using ultrasonic method, yet more sophisticated device or special sensors are required to measure the ice thickness completely. And the defection of ice plate is measured using LVDT to compute the characteristic length of ice plate on the fluid, which is used to get the effective Young's modulus of model ice.
Modal Property Estimation of Tapered Cantilever Pipe-type Cracked Beam
Lee, Jong Won ; Kim, Sang Ryul ; Kim, Bong Ki ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 361~368
DOI : 10.7734/COSEIK.2014.27.5.361
Modal properties for tapered cantilever pipe-type beam is identified by applying the boundary conditions to a general solution for tapered beam. A bending stiffness for cracked beam is constructed based on an energy method for tapered cantilever thin-walled pipe, which has a through-the-thickness crack, subjected to bending. Then the natural frequencies and mode shapes of a tapered cantilever thin-walled cracked pipe are identified. It can be found that the phenomenon of the bending stiffness distribution along the beam length of the cracked beam is quite reasonable, the natural frequencies are decreased as the crack sizes are increased, and the mode shapes are changed due to the crack. This results may be used to the vibration-based crack identification for the tapered cantilever pipe-type tower structures.
Collision Analysis of Submerged Floating Tunnel by Underwater Navigating Vessel
Hong, Kwan-Young ; Lee, Gye-Hee ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 369~377
DOI : 10.7734/COSEIK.2014.27.5.369
In this paper, to recognize the collision behavior between a submerged floating tunnel(SFT) and underwater navigation vessel(UNV), both structures are modeled and analyzed. The SFT of collision point is modeled tubular section using concrete with steel lining. The other part of SFT is modeled elastic beam elements. Mooring lines are modeled as cable elements with tension. The under water navigation vessel is assumed 1800DT submarine and its total mass at collision is obtained with hydrodynamic added mass. The buoyancy force on SFT is included in initial condition using dynamic relaxation method. The buoyancy ratio (B/W) and the collision speed are considered as the collision conditions. As results, energy dissipation is concentrated on the SFT and that of the UNV is minor. Additionally, the collision behaviors are greatly affected by B/W and the tension of mooring lines. Especially, the collision forces are shown different tendency compare to vessel collision force of current design code.
Multi-flexible Dynamic Modeling and Wheel Load Analysis of a Rubber Tired Gantry Crane in Container Cargo Working
Kim, Jungyun ; Kim, Jingon ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 379~384
DOI : 10.7734/COSEIK.2014.27.5.379
This article describes the dynamic behaviors of a rubber tired gantry crane(RTGC) under typical load conditions which are used in the design of gantry cranes. In order to investigate the dynamic characteristics of an RTGC, we developed a finite element crane model for its huge structure. The finite element model was validated with the modal test results, e.g., natural frequencies and normal modes. And other components of RTGC were converted into detailed 3D CAD models and finally transformed to rigid body models in a dynamic simulation program ADAMS. The load conditions considered in this paper were a normal operating condition(OP1) and container hanging condition with no external loads. As a result, we could find there was large influence of crane's vibration owing to its structural stiffness and deformation. And the vibration of crane could made the movements of RTGC, which occurs crash or malfunction of crane works.
Seismic Responses of Seismically-Isolated Nuclear Power Plants considering Aging of High Damping Rubber Bearing in Different Temperature Environments
Park, Junhee ; Choun, Young-Sun ; Choi, In-Kil ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 385~392
DOI : 10.7734/COSEIK.2014.27.5.385
The isolators have been generally used to reduce a seismic force. If the isolators apply to the nuclear power plants(NPPs), the durability and capacity for the structures and equipments should be ensured during the life time. In this study, the long-term behavior of isolated NPPs was analyzed for ensuring the seismic safety. The properties of isolator due to the age-related degradation were analyzed. And the seismic behavior of isolated buildings was analyzed by considering the aging of rubber bearings in different temperature environments. According to the analysis results, the natural frequency of structures was increased with time. But the maximum acceleration and maximum displacement of isolated structures have not changed significantly. Although the damaged of structure did not occurred by aging of isolators, it was presented that the spectral acceleration at the target frequency of isolated structure increased with the temperature. Therefore the isolators in the isolated buildings should be carefully designed and manufactured considering the temperature-dependancy of rubber material.
Evaluation of the Coefficient of Thermal Expansion of Constituents in Composite Materials using an Inverse Analysis Scheme
Lim, Jae Hyuk ; Sohn, Dongwoo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 393~401
DOI : 10.7734/COSEIK.2014.27.5.393
In this paper, we propose an evaluation scheme of the coefficients of thermal expansion (CTE) of constituents in composite materials using an inverse analysis. The size of constituents typically is about a few micrometers, which makes the identification of material properties difficult as well as the measurement results inaccurate. The proposed inverse analysis scheme, which is combined with the Mori-Tanaka method for predicting an equivalent CTE of composite materials, provides the CTE of the constituents in a straightforward manner by minimizing the cost function defined in lamina scale with the steepest descent method. To demonstrate the effectiveness and accuracy of the proposed scheme, the CTEs of several fibers (glass fiber, P75, P100, and M55J) embedded in matrix are evaluated and compared with experimental results. Furthermore, we discuss the effects of uncertainty of laminar and matrix properties on the prediction of fiber properties.
Design Program and Economic Evaluation for Hollow RC Bridge Columns with Reinforcement Details for Material Quantity Reduction
Kim, Tae-Hoon ; Son, Yun-Ki ; Yang, Nam-Seok ; Lee, Seung-Hoon ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 403~412
DOI : 10.7734/COSEIK.2014.27.5.403
This paper presents special-purpose design program and plastic design results for hollow RC bridge columns with reinforcement details for material quantity reduction. The developed reinforcement details has economic feasibility and rationality and makes construction periods shorter. This study documents the economic evaluation of hollow reinforced concrete bridge column systems with reinforcement details for material quantity reduction and presents conclusions based on the application findings. As a result, the proposed reinforcement details for material quantity reduction were designed prior to the existing reinforcement details in terms of structural rationality, constructability, and economic.
Evaluation of Punching Shear for Flat Plates Using GFRP Plate Shear Reinforcement
Lee, Young Hak ; Kim, Min Sook ; Hwang, Seung Yeon ; Choi, Jinwoong ; Kim, Heecheul ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 413~420
DOI : 10.7734/COSEIK.2014.27.5.413
The purpose of this study is to experimentally investigate the shear behavior of flat plate that reinforced by embedded GFRP(glass fiber reinforced polymer) plate with openings. Shape of the GFRP shear reinforcement is a plate with several openings to ensure perfect integration with concrete. The test was performed on 7 specimens to check shear strength of flat plate that reinforced by GFRP plate. The parameters include the spacing of the shear reinforcement and amount of the shear reinforcement. The result of test showed that when amount of shear reinforcement was increased, shear strength improved. The result of test showed that maximum shear strength was confirmed when spacing of shear reinforcement was 0.3d. The calculation of the shear strength of reinforced flat plate with GFRP plate based on the KCI was compared with the test results.
Study on the Structural Optimization based on Equivalent Static Load under Dynamic Load
Kim, Hyun-Gi ; Kim, Euiyoung ; Cho, Maenghyo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 421~427
DOI : 10.7734/COSEIK.2014.27.5.421
Most of the structure of the real world is influenced under dynamic loads. However, when structure analysis and the structural optimization is performed, it is assumed that the static load acts on structure. When considering the actual load of dynamic loads in order to take into account a variety of loads, computational resources and time becomes a big burden in terms of cost. However, considering only the simple static load condition is not preferable for structural safety. For this reason, a lot of studies have been conducted trying to compensate this trouble by applying weight factor or replacing dynamic load with the equivalent static load. In this study, structural optimization techniques for structures under dynamic loads is proposed by applying the equivalent static load. From previous study, after determining the positions of equivalent static load based on primary degrees of freedom, the equivalent static load is calculated through the optimization process. In this process, the equivalent static load optimization of previous research is complemented by adding constraints to avoid excessively large load extraction. In numerical examples, dynamic load is applied to the truss structure and the plate. Then, the reliability of the proposed optimization technique is verified by carrying out size optimization with the equivalent static load.
Nonlinear Seismic Analysis of a Three-dimensional Unsymmetrical Reinforced Concrete Structure
Lim, Hyun-Kyu ; Lee, Young-Geun ; Kang, Jun Won ; Chi, Ho-Seok ; Cho, Ho-Hyun ; Kim, Moon-Soo ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 429~436
DOI : 10.7734/COSEIK.2014.27.5.429
This paper presents the seismic performance of a geometrically unsymmetrical reinforced concrete building considering torsional effect and material nonlinearity of concrete and steel. The reinforced concrete building is a structure for seismic performance evaluation in the SMART-2013 international benchmark program. Nonlinear constitutive models for concrete and steel were constructed, and their numerical performance was demonstrated by various local tests. Modal analysis showed that the first three natural frequencies and mode shapes were close to the experimental results from the SMART-2013 program. In the time history analysis for low-intensity seismic loadings, displacement and acceleration responses at sampling points were similar to the experimental results. In the end, nonlinear time history analysis was conducted for Northridge earthquake to predict the behavior of the reinforced concrete structure under high-intensity seismic loadings.
A Study on the Determination of Reference Parameter for Aircraft Impact Induced Risk Assessment of Nuclear Power Plant
Shin, Sang Shup ; Hahm, Daegi ; Choi, In-Kil ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 437~450
DOI : 10.7734/COSEIK.2014.27.5.437
In this study, we developed a methodology to determine the reference parameter for an aircraft impact induced risk assessment of nuclear power plant (NPP) using finite element impact analysis of containment building. The target structure used to develop the method of reference parameter selection is one of the typical Korean PWR type containment buildings. We composed a three-dimensional finite element model of the containment building. The concrete damaged plasticity model was used for the concrete material model. The steels in the tendon, rebar, and liner were modeled using the piecewise-linear stress-strain curves. To evaluate the correlations between structural response and each candidate parameter, we developed Riera's aircraft impact force-time history function with respect to the variation of the loading parameters, i.e., impact velocity and mass of the remaining fuel. For each force-time history, the type of aircraft is assumed to be a Boeing 767 model. The variation ranges of the impact velocity and remaining fuel percentage are 50 to 200m/s, and 30 to 90%, respectively. Four parameters, i.e., kinetic energy, total impulse, maximum impulse, and maximum force are proposed for candidates of the reference parameter. The wellness of the correlation between the reference parameter and structural responses was formulated using the coefficient of determination (
). From the results, we found that the maximum force showed the highest
value in most responses in the materials. The simplicity and intuitiveness of the maximum force parameter are also remarkable compared to the other candidate parameters. Therefore, it can be concluded that the maximum force is the most proper candidate for the reference parameter to assess the aircraft impact induced risk of NPPs.
Optimization of Quantity of Core Walls in Tall Buildings with StrAuto Analysis
Choi, Hyunchul ; Lee, Yunjae ; Kim, Chee-Kyeong ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 451~458
DOI : 10.7734/COSEIK.2014.27.5.451
This study is a practical research for setting a process of making references of design decision and guidlines of limitation in the movement from the design development to the construction design by StrAuto. StrAuto, as a parametric modeling and optimization tool for building structure, enables a quantity of design cases to be analyzed automatically by changing parameters of sturctural properties. So the designer using StrAuto can check a lot of analysis data crossing thousands of cases, see which case is out of acceptable range, and make a decision for design and optimization. In this thesis, the application of StrAuto optimization process to the residence tower UIC project shows the practical applicability in the construction design and value engineering. StrAuto optimized ideally volume of core walls by 31.3% and lead the final revised model applied to the construction design to reduce volume by 18.1%. The significance of this research is the implementation of process that the designer can quickly review a number of cases and get a direction for construction design and optimization after design development.
Simplified Analysis of Superstructure Section Considering Diaphragm and Optimum Design Conditions for ILM Bridge
Lee, Hwan-Woo ; Park, Yong-Jin ;
Journal of the Computational Structural Engineering Institute of Korea, volume 27, issue 5, 2014, Pages 459~467
DOI : 10.7734/COSEIK.2014.27.5.459
ILM(Incremental Launching Method) bridges pass both the middle of spans and supports during launching. The launching noses are used to minimize the maximum positive moments and negative moments of the superstructure occurring during launching for ILM bridges. In this study, the simplified analysis formula considering diaphragm to calculate the bending moment that occurs during launching is induced and analyzes the optimum design conditions considering diaphragm. The accuracy of the proposed simplified analysis formular compared to the MIDAS Civil has an error of less than 5%. There is a difference up to 13% in the moment between the cases when the diaphragm is considered and is not. In addition, the criteria for deciding the unit weight of equivalent cross section and average stiffness value of equivalent cross section that can be applied to the simplified analysis formula is proposed. In this study, an effective way to optimize the launching nose is proposed that the optimum design is taken in the condition of minimizing the negative moment because of the mechanic characteristic of ILM bridges.