• Journal of the Korea institute for structural maintenance and inspection
• /
• v.8 no.2
• /
• pp.247-258
• /
• 2004

The composite shell element is developed for the solution of undamped forced vibration problem of composite curved panels. The finite element used in the current study is an 4-node enhanced assumed shell element with six degrees of freedom per node. The composite shell element is free of both shear and membrane locking phenomenon by using the enhanced assumed strain(EAS) method. A modification to the first-order shear deformation shell theory is proposed, which results in parabolic thorough-thickness distribution of the transverse shear strains and stresses. It eliminates the need for shear correction factors in the first order theory. Newmark's direct integration technique is used for carrying out the integration of the equation motion, to obtain the repones history. Parametric studies of curved composite panels are carried out for forced vibration analysis by geometrical shapes and by laminated composite; such as fiber orientation, stacking sequence.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.23 no.2
• /
• pp.191-198
• /
• 2010

This study investigated that the stress reduction of single edge cracked plates with patch repairs according to different type of patching such as material, size and thickness of patch and adhesive as well as single sided or double sided patches. As a numerical tool, the p-convergent partial layerwise model has been employed. The proposed model is formulated by assuming piecewise linear variation of in-plane displacement and a constant value of out-of-plane displacements across thickness. The integrals of Legendre polynomials are chosen to define displacement fields and Gauss-Lobatto numerical integration is implemented in order to directly obtain maximum values occurred at the nodal points of each layer without other extrapolation techniques. Also, total strain energy release rate method is adopted to obtain stress intensity factors. Numerical examples are presented not only to demonstrate the stress reduction effect in terms of non-dimensional stress intensity factor and deflection with respect to different type of patch repairs, but also the accuracy of proposed model.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.3
• /
• pp.267-275
• /
• 2009

This paper presents the p-convergent coupling element on the basis of the ESSE(equivalent single layer shell element) and the PLLE(partial-linear layerwise element) to analyze laminated composite plates. The ESSE is formulated by the degenerated shell theory, on the other hand, the assumption of the PLLE is piecewise linear variation of the in-plane displacement and a constant value of lateral displacement across the thickness. The proposed finite element model is based on p-convergence approach. The integrals of Legendre polynomials and Gauss-Lobatto technique are chosen to interpolate displacement fields and to implement numerical quadrature, respectively. This study has been focused on the verification of p-convergent element. For this purpose, various finite element multiple models associated with the combination of ESSE and PLLE elements are tested to show numerical stability. The simple examples such as a cantilever beam subjected vertical load and a plate with tension are adopted to evaluate the performance of proposed element.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.8
• /
• pp.698-707
• /
• 2011

This paper is to analyze the stability of the thick plate on inhomogeneous Pasternak foundation, with linearly varying thickness and concentrated mass by finite element method. To verify this finite element method, the results of natural frequencies and buckling stresses by the proposed method are compared with the existing solutions. The dynamic instability regions are decided by the dynamic stability analysis of the thick plate on inhomogeneous Pasternak foundation, with linearly varying thickness and concentrated mass. The non-dimensional Winkler foundation parameter is applied as 100, 1000 and non-dimensional shear foundation parameter is applied as 5. The tapered ratios are applied as 0.25 and 1.0, the ratios of concentrated mass to plate mass as 0.25 and 1.0, and the ratio of in-plane force to critical load as 0.4. As the result of numerical analysis of the thick plate on inhomogeneous Pasternak foundation for $u{\times}v=300cm{\times}300cm$ and $a{\times}b=600cm{\times}600cm$, instability areas of the thick plate which has the larger rigidity of inner area are farther from ${\beta}$-axis and narrower than those which has the larger rigidity of outer area.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.1
• /
• pp.1-12
• /
• 2002

To obtain more accurate responses of laminated composite structures, the effect of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate need to be considered in the analysis. The improved higher-order theory is used to determine the deflections and natural frequencies of laminated composite structures. A quasi-elastic method is used for the solution of viscoelastic analysis of the laminated composite plates and sandwiches. Solutions of simply-supported laminated composite plates and sandwiches are obtained and the results are compared with those by the 3D elasticity theory and other theories. The improved theory proposed in this paper is shown to predict the deflections and natural frequencies more accurately than all other theories.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.3
• /
• pp.8-15
• /
• 2018

An experiment was carried out to evaluate the lateral torsional stability of a girder with respect to the location and magnitude of prestressing force. The test of evaluating the lateral displacement and stability of a girder could cause an unexpected result due to various parameters, such as material nonlinearity, initial geometric imperfections, prestressing force, and loading and support conditions. Therefore, a small model testing was programmed to control the various parameters and assess the lateral torsional stability with respect to the prestressing force. This study proposed and fabricated an experimental apparatus that can satisfy the loading and in-plane and out-of-plane support conditions and also contol the prestressing force. The result of the experiment showed that the lateral torsional stability increased when the prestressing force was applied in the bottom flange of the girder. As a result, this study proposed an analytical equation that can account for the effect of the prestressing force in the lateral torsional stability of a girder.

• Journal of Korean Society of Steel Construction
• /
• v.12 no.2 s.45
• /
• pp.187-196
• /
• 2000

In this paper, stability analysis is carried out for the out of plane behaviors under compressive loads to the direction of the generator in anisotropic cylindrical shells. It is not easy to obtain the analytic solutions about the stability analysis of anisotropic cylindrical shells consisted of composite materials. For solving this problems, this paper used the finite difference method which is one of the numerical methods. Geometrical property of cylindrical shells transforms the compressive loads into the inplane behaviors. This paper studied the change of stiffness in the direction of the circumferential and stability of shells according to change of fiber angle, curvature, subtended angle and aspect ratio. From result of this study, anisotropic cylindrical shells under compressive loads to the direction of the generator vary greatly with respect to the change of the circumferential stiffness. Therefore, it will be more safe to strengthen the circumferential stiffness of anisotropic cylindrical shells under compressive loads.

• Journal of Korean Society of Steel Construction
• /
• v.21 no.3
• /
• pp.277-287
• /
• 2009

The objective of this study was to experimentally investigate the structural behavior of steel plate concrete walls with vertical ribs (SSC walls), to compare the experimental results with the currently applied evaluation equations, and to obtain information that would be useful in the development of design equations for SSC walls. SSC test specimens that were subjected to in plane shear forces and bending moments were fabricated and tested. The experimental results show that the effect of vertical ribs on the structural behavior of SSC walls may be neglected, and that the confinement effect of concrete on the steel plates on both sides of the walls was negligible. The comparison of the experimental results with the evaluation equations showed that the structural behavior of SSC walls under shear control is close to that of the evaluation equations, but that the behavior of SSC walls under larger bending moments is not very close to that of the evaluation equations. The current evaluation equations for USC walls may be applied to the design of SSC walls because the structural walls of nuclear power plants are not subjected to large in plane bending moments.

• Journal of the Society of Disaster Information
• /
• v.13 no.2
• /
• pp.249-257
• /
• 2017

Recently, a cable disconnection accident occurred due to a lightning strike at the Seohae Bridge located in Dangjin-Pyeongtaek City. This is a natural occurrence, but it is a recall that it is very important to review the safety issues due to the disconnection of cable bridges. In other words, the role of cables in cable bridges has a profound effect on the safety of the structure, and it has become necessary to grasp the effect on the entire structural system. The cable bridge is an economic bridge that builds the main tower and supports the bottom plate by cable. The influence of the cable is the main member, which is a big influence on the safety of the whole bridge system. In the cable-stayed bridge, the cables exhibit nonlinear behavior because of the change in sag, due to the dead weight of the cable, which occurs with changing tension in the cable resulting from the movement of the end points of the cable as the bridge is loaded. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

• Journal of the Society of Naval Architects of Korea
• /
• v.33 no.3
• /
• pp.66-80
• /
• 1996

Recently, HT steel has been widely used in structure, and this enables to reduce the plate thickness. To use the HT steel effectively for a ship hull, the plate thickness becomes thin so that plate buckling may take place. Therefore, precise assessment of the behaviour of plat above primary buckling load is important. The plate under the load, that is called, secondary buckling load may undergo abrupt changes in wave form after primary buckling. This is very important when the collapse strength of the whole structures is considered. From this point of view, this paper discusses secondary buckling behaviour of thin plate under inplane compressive loading. A elastic large deflection analysis of plates with initial imperfection is performed assuming uniaxial compression, respectively, and the influence of secondary buckling is investigated. It is known that square plate is not influenced by non-symmetrical deflection coefficient but influenced by symmetrical deflection coefficient. Also, it has been found that rectangular plate($\alpha$=a/b) is influenced by all deflection coefficient, and the reduction of inplane stiffness of the plate after primary buckling is continued.