• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.69-82
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• 1991

The dynamic stability of the long vertical beam subjected to the periodic axial load is investigated. As a solution method, the Galerkin's method is used to obtain a set of coupled Mathieu type equations. To obtain the stability chart, both the perturbation method and numerical method are used, and the results of the both methods are compared with each other. The stability regions for the various boundary conditions are obtained, Also the effects of the viscous damping, the mean tension and the multi-frequency parametric excitation are studied in detail.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.516-528
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• 2009

Form the application of long rail system the non-ballast steel plate bridges, fatigue strength increase and rail noise reduction can be expected. This is mainly form the reduction of the rail impact at the rail joint locations which already made to behave together from welds. In the high speed rail, application of long rail system is essential because without long rail system, the required serviceability level can not be achieved. But even with this long rail systems, the thermal expansion from the girder can not be absorbed in the normal bearing systems, and these expansion cause between girder and rail. Also unexpected rail buckling and fracture through rail thermal tension may happen. It was found through numerical analysis and field measurement that these problems can be avoided by semi-fixed bearing system. In this study, the benefits of non-ballast plate bridge through long rail system, especially at the point of girder stability, girder stiffness increase and bearing maintenance will be reviewed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.698-703
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• 2007

A simplified model which incorporates the moment-axial tension interaction of the double-span beams in a column-removed steel frame is presented in this paper. To this end, material and geometric nonlinear parametric finite element analyses were conducted for the double-span beams by changing the beam span to depth ratio and the beam size within some practical ranges. The beam span to depth ratio was shown to be the most influential factor governing the catenary action of the double-span beams. Based on the parametric analysis results, a simplified piecewise linear model which can reasonably describe the vertical, resisting force versus the beam chord rotation relationship was proposed. It was also shown that the proposed method can readily be used for the energy-based progressive collapse analysis of steel moment frames.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.73-79
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• 2009

In order to investigate the formability of friction stir welded(FSW) tailor welded blanks(TWB) with respect to the base material's directional combination, aluminum alloy AA6111-T4 sheets were welded with three different conjoining types: RD-RD, TD-RD and TD-TD. Here, RD and TD represent rolling and transverse directions, respectively. For experimental formability study, three tests with gradual complexity were performed: the simple tension test with various weld line directions for uni-axial elongation, the hemisphere dome stretching test for biaxial stretching and the cylindrical cup deep drawing test. As a result, all three forming tests showed that RD-RD type samples exhibited the best formability, while TD-TD type sheets showed the least formability performance.

• Bulletin of the Society of Naval Architects of Korea
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• v.7 no.1
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• pp.13-26
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• 1970

An elastic plate bar jointed to a rigid bar is considered. The bar is subjected to uniform axial tension. A theoretical approximate solution is obtained in an infinite hyperbolic series form and some numerical results for various Poisson's ratios are presented. A rubber plate joined to a strong wooden plate has been tested to obtain an experimental data and the results are compared with theoretical ones. Two values for vertical displacements are in good agreement but it is not satisfactory for horizontal displacements. The conclusion arrived at are as follow : The natures of stress distributions and deformed shapes given by above theoretical solution are compatible in mechanical sense. The magnitudes of stress and displacement components would not be reliable for exact works. A sharp shear stress concentrations are detected at the both ends of the joint.

• Steel and Composite Structures
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• v.20 no.1
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• pp.43-56
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• 2016

Polyurethane foam with low density used in sandwich panels is examined in the paper. A series of experiments was carried out to identify mechanical parameters of the foam. Various experimental methods were used for determining the shear modulus, namely a four and three point bending tests (the most common in engineering practice), a double-lap shear test and a torsion test. The behavior of PU in axial compression and tension was also studied. The experiments revealed pronounced anisotropy of the PU foam. An orthotropic model is proposed. Limitations of application of isotropic model of PU in engineering practice is also discussed.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.937-940
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• 2006

According to the analysis of tension failure mechanism of UHSC specimen, one modified model based on ACK model by the introduction of partial debonding energy of non-first cracks and by the application of steel fiber number on unit area is presented in this paper. It can be used to explain the evolution mechanism of multiple cracking and pseudo strain hardening of UHSC. From the numerical results, to increase steel fiber length and to reduce steel fiber diameter in some region all can reduce the fiber volume fraction with the same multiple cracks for economic design of UHSC.

• Journal of the Korean Institute of Rural Architecture
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• v.18 no.3
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• pp.35-42
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• 2016

For the reason of economy, farmers and structural engineers prefer the vinyl house frame members that have the lightest cross sections. Therefore, in order to reach this aim, rod bracing system is the best method for multiple vinyl house frames. In this study, wire rods (tension members) are used to be bracing members in multiple vinyl house frames. The effects of additional wire rods in the frames are investigated by the variations of the bending moments, axial forces, displacements and combined stresses in the main frames that are reinforced by different shapes of rod bracing system. Vinyl house frames are usually made by steel pipe members and collapsed by the excessive wind and snow loads. Two kinds of bracing models are used for wind and snow loads separately in this study. The effective bracing models for each load are finally figured out.

• Journal of Mechanical Science and Technology
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• v.18 no.7
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• pp.1159-1168
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• 2004

In this paper, a spectral element model is derived for the axially moving viscoelastic beams subject to axial tension. The viscoelastic material is represented in a general form by using the one-dimensional constitutive equation of hereditary integral type. The high accuracy of the present spectral element model is verified first by comparing the eigenvalues obtained by the present spectral element model with those obtained by using the conventional finite element model as well as with the exact analytical solutions. The effects of viscoelasticity and moving speed on the dynamics of moving beams are then numerically investigated.

• Journal of the Korean Society for Railway
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• v.6 no.2
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• pp.129-134
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• 2003

This paper investigates the dynamic characteristics of a beam axially moving over multiple elastic supports. The spectral element matrix is derived first for the axially moving beam element and then it is used to formulate the spectral element matrix for the moving beam element with an interim elastic support. The moving speed dependance of the eigenvalues is numerically investigated by varying the applied axial tension and the stiffness of the elastic supports. Numerical results show that the fundamental eigenvalue vanishes first at the critical moving speed to generate the static instability.