• Tunnel and Underground Space
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• v.9 no.3
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• pp.185-193
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• 1999

This paper presents results of dynamic analysis for a bridge in intersection part of two tunnels subjected to moving vehicle load. Since such a bridge system is very unusual due to the fact that it is located in tunnel, the dynamic characteristics of the structure can not be assumed as conventional one. The structure investigated in this study it a reinforced concrete bridge in the intersection part of Namsan Tunnel-1 and Tunnel-2 in Seoul. It is supported by temporary steel structure which shall be constructed during the period of replacing lining in Tunnel-2. Dynamic analysis was carried out for the system using a finite element model constructed by general purpose FE program SAP2000. For this purpose, the structure, lining of tunnels, and surrounding rock were represented by finite elements, while the rock region it truncated and on its outer boundary viscous dampers were placed to simulate radiation of elastic waves generated tunnels. Several types of vehicle with various driving velocities were considered in this analysis. The FE model including vehicle loadings was verified by comparing calculated peak particle velocity with the measured one. From the analysis, the impart factor for the bridge was estimated as 0.21, which indicates that the use of upper bound for the impact factor in design code is reasonable for this kind of bridge system.

• Journal of the Korea Convergence Society
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• v.7 no.1
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• pp.161-166
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• 2016

Deformation, stress and fatigue life due to the configuration of tie rod end are investigated in this study. Tie rod ends with the total three kinds of configurations are modelled with three dimensions through CATIA program and the simulation analysis is carried out with the ANSYS finite element analysis program. There are the models of A, B and C by the configuration of the rod end. As this study result, maximum deformation, maximum equivalent stress and maximum fatigue life of A type model are shown to be 0.0614mm, 160.27MPa and 336,930cycles respectively. And maximum deformation, maximum equivalent stress and maximum fatigue life of B type model are shown to be 0.0648mm, 90.889MPa and 1,171,000cycles respectively. Maximum deformation, maximum equivalent stree and maximum fatigue life of C type model are also shown to be 0.0402mm, 84.794MPa and 20,000,000cycles respectively. The durability of the models of tie rod ends through the values of this result could be estimated and the data for the design and development of more improved tie rod end could be secured. And it is possible to be grafted onto the convergence technique at design and be shown as the esthetic sense.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.41-70
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• 1999

The benefits of utilizing internal reinforced members, such as soil nails and ground anchors, in maintaining stable excavations and slopes have been known among geotechnical engineers to be very effective. Occasionally, however, both soil nails and ground anchors are simultaneously used in one excavation site. In the present study, a method of limit equilibrium stability analysis of the excavation zone reinforced with the vertically or horizontally mixed nail-anchor system is proposed to evaluate the global safety factor with respect to a sliding failure. The postulated failure wedges are determined based on the results of the $FLAC^{2D}\; 및\; FLAC^{3D}$ program analyses. This study also deals with a determination of the required thickness of the shotcrete facing. An excessive facing thickness may be required due to both the stress concentration and the relative displacement at the interface zone between the soil nailing system and the ground anchor system. A simple finite element method of analysis is presented to estimate the corresponding relative displacement at the interface zone between two different support systems. As an efficient resolution to reduce the facing thickness, the modified bearing plate system is also proposed. Finally with various analysis related to the effects of design parameters, the predicted displacements are compared with the results of the $FLAC^{2D}$ program analyses.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.567-575
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• 2001

In order to consider statistical properties of probability variables used in the structural analysis the conventional approach using the safety factor based on past experience usually estimated the safety of a structure Also the real structures could only be analyzed with the error in estimation of loads material characters and the dimensions of the members. But the errors should be considered systematically in the structural analysis Safety of structure could not precisely be appraised by the traditional structural design concept Recently new aproach based on the probability concept has been applied to the assessment of structural safety using the reliability concept Thus the computer program by the Probabilitstic FEM is developed by incorporating the probabilistic concept into the conventional FEM method. This paper estimated for the reliability of a plane stress structure by Advanced First-Order Second Moment method using von Mises, Tresca and Mohr-Coulomb failure criterions. Verification of the reliability index and failure probability of attained by the Monte Carlo Simulation method with the von Mises criterion were same as PFEM, but the Monte Carlo Simulation were very time-consuming. The variance of member thickness and load could influence the reliability and failure probability most sensitively among the design variables from the results of the parameter analysis. The proper failure criterion according to characteristic of materials must be used for safe design.

• Geotechnical Engineering
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• v.12 no.6
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• pp.127-138
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• 1996

The in-situ consolidation behavior of drainage system-installed deposits has three dimensional characteristics. Therefore, for an approximate 2-D plane strain consolidation analysis, it is necessary to convert the 3-D spatial flow of actual cases into the laminar flow simulated by the 2-D plane strain model. . In this paper, in order to properly model the effect of three dimensional characteristics, an equivalent and efficient model has been applied in a finite element technique for the analysis of the drainage system-installed soil deposits. The equivalent two dimensional model involves equivalent permeabilities and drainage widths. To validate the equivalent two dimensional model, three dimensional analyses were per formed by using the ABAQUS program and the results of 3-D analyses were compared with those of the 2-D analyses. By using the proposed equivalent model, one may be able to appropriately predict the consolidation behavior of drainage system-installed soft deposits.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.1-8
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• 2018

The fuel pump, which is used for an aircraft, was first developed in Korea through the Civil-Military Dual Components Development Program. The BLDC motor type, which is superior to the DC brush motor when considering efficiency, endurance, and explosive environmental characteristics, was applied to the fuel pump given its capacity and operating condition. The magnetic flux of the permanent magnet was analyzed based on the magnet flux density equation, using the Maxwell equation and the environmental condition. The motor performance, according to the load, was analyzed using the finite element method in order to design validation. The motor assembly was developed by designing the motor drive and the EMI filters. The performance test results of the motor assembly for the fuel boost pump were consistent with the analysis.

• Journal of the Korean Geotechnical Society
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• v.15 no.6
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• pp.121-130
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• 1999

The objective of this study is to perform finite element analyses(FEA) using the anisotropic hardening constitutive model on the basis of the total stress concept. An anisotropic hardening model was then developed to solve the problem and its mathematical formulations and experimental verifications were also described. In a companion paper, the constitutive equation will be formulated for accurate and efficient solutions of FEA, and coded into a nonlinear analysis program, and finally a field problem will be analyzed. The proposed model includes the failure criterion of a von Mises type and the anisotropic hardening rule based on the generalized isotropic hardening description, which can model the nonlinearity and the anisotropy of the stress-strain relationship. As a result this study could verty the experimental results for UU triaxial tests, CU triaxial tests for overconsolidated samples, and anisotropic loading tests with the rotation of principal stress axes for $K_0$consolidated samples.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.717-726
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• 2005

This study investigates the bearing pressure distribution and design of an H-section steel column baseplate under concentric loading. In general, the size and thickness of the baseplate are determined with the assumption that the bearing pressure of the column baseplate is distributed uniformly. When the column is loaded lightly, however, the baseplate becomes smaller andthinner and the bearing pressure of the baseplate is distributed non-uniformly. In this study, the distribution of the bearing pressure is investigated using the experimental method and the analytical method. Seven specimens of the H-section steel column baseplate were fabricated and tested. The analysis of the specimens was performed using the finite element analysis program, ANSYS. It is not appropriate to use the Limit State Design,which assumes that the bearing pressure of the baseplate is distributed uniformly,because the bearing pressure is distributed non-uniformly and is concentrated under the column sectio.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.52-58
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• 2012

Roll forming process is one of the most widely used processes in the world for forming metals such as a furniture drawer guide or an up and down slide guide. It can manufacture goods of the uniform cross section on a large scale throughout the continuous processing. In the domestic design and manufacture, roll forming process for production is taking most of the method of 2-point under rail slide. However, this method is vulnerable to the structural strength and stiffness is not suitable for high load conditions. Therefore, through systematic study of high load, low noise 3-point ball type of under rail slide its own design and manufacturing technology is the need to build. In this paper, to make center member of 3-point ball-type under rail slide for the refrigerator doors, the roll forming modeling and simulation are performed. Tensile test is performed about SCP-1 1/2H for determine the mechanical properties of materials. Modeling and simulation of roll forming is used MSC.MARC software of a dedicated analysis program used by rigid plastic finite element method. Interference between the roll and the final shape are predicted from the results of the simulation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.59-70
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• 1992

Inelastic nonlinear behavior of a hyperbolic cooling tower under wind loading is studied using a finite element program developed on a Cray Y-MP. Convergence studies for the elastic and inelastic analyses are performed using three mesh models. It is shown that the mesh convergence plays an important role in accurately predicting the inelastic behavior of a cooling tower. Even though the cooling tower resists the applied forces through membrane stresses, it is found that the bending stresses play an important role in the failure and behavior of the cooling tower. The present analysis gives a shape factor of 1.48, which indicates a significant redistribution of meridional stresses. It is further evidenced by the distribution of meridional reinforcement yielding which reaches up to $30^{\circ}$ from the windward meridian. The present practice of using elastic analysis for calculating the design stresses appears to be at least safe and conservative. A more comprehensive study should lead to conclusions that would allow use of a higher-than-one shape factor, thus requiring less meridional reinforcement than the present design method does.