• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.427-436
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• 2006

The classical buckling theory assumes that prebuckling behavior is linear and that the effect of prebuckling deformations on buckling can be ignored. However, when the rise to span ratio decreases, prebuckling deformation cannot be ignored and the symetrical buckling strength can be smaler than the asymetrical buckling strength. Finally, arches can fail due to snap-through buckling. This paper investigates the non-linear behavior and strength of pin-ended parabolic shallow arches using the non-linear governing differential equation of shallow arches. These results were compared with the solution for the symmetrical buckling load of pin-ended parabolic shallow arches was suggested.

• Journal of Korean Society of Steel Construction
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• v.13 no.6
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• pp.683-691
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• 2001

Numerical methods are developed for solving the elastica and buckling load of tapered columns with shear deformation, subjected to a compressive end load. The linear, parabolic and sinusoidal tapers with the regular polygon cross-sections are considered, whose material volume and span length are always held constant. The differential equations governing the elastica of buckled column are derived. The Runge-Kutta method is used to integrate the differential equations, and the Regula-Falsi method is used to determine the rotation at left end and the buckling load, respectively. The numerical methods developed herein for computing the elastica and the buckling loads of the columns are found to be efficient and reliable.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.81-92
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• 2010

In design of steel frames, it is generally believed that elastic system buckling analysis cannot predict real behaviors of structures, while inelastic system buckling analysis can give informative buckling behaviors of individual members considering inelastic material behavior. However, the use of Euler buckling equation with these system buckling analyses have the inherent problem that the methods evaluate unexpectedly large effective lengths of members having relatively small axial forces. This paper proposes a new method of obtaining elastic and inelastic effective lengths of all members in steel frames. Considering a fictitious axial force factor for each story of frames, the proposed method determines the effective lengths using the inelastic stiffness reduction factor and the iterative eigenvalue analysis. In order to verify the validity of the proposed method, the effective lengths of example frames by the proposed method were compared to those of previously established methods. As a result, the proposed method gives reasonable effective lengths of all members in steel frames. The effect of inelastic material behavior on the effective lengths of members was also discussed.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.94-104
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• 1999

Plate buckling is very important design criteria when the ship is composed of high tensile steel plates. In general, the plate element contributes to inplane stiffness against the action of inplane load. If the inplane stiffness of the plating decreases due to buckling including the secondary buckling, the flexural rigidity of the cross section of a ship's hull also decreases. In these cases, the precise estimation of plate's behaviour after buckling is necessary, and geometric nonlinear behaviour of isolated plates is required for structural system analysis. In this connection, the author investigated the geometric nonlinear behaviour of simply supported rectangular plates under uniaxial compression in the longitudinal direction in which the principle of minimum potential energy method is employed. Based on the energy method, elastic large deflection analysis of isolated palate is performed and simple expression are derived to discuss the bifurcation paint type buckling and limit point type buckling.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.77-84
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• 2007

The elastic buckling strength of a corrugated pipe made of orthotropic material was evaluated. The height and length of a corrugated wave and the thickness of the pipe were considered as factors affecting the buckling strength of the pipe. And also, the ratio of the longitudinal stiffness and transverse stiffness were considered as parameters affecting on the buckling strength of a pipe made of orthotropic material. Buckling strengths of various corrugated pipes with different shapes and stiffness ratio were evaluated by FE analyses. And a formula to estimate the elastic buckling strength was suggested by regression of FE analysis results. Analysis results show that a corrugated pipe has superior buckling strength to a general flat pipe and the suggested formula estimates accurate buckling strength of the corrugated pipe made of orthotropic material.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2491-2500
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• 1996

An experimental and analytical investigation is performed to study the buckling behavior of composite laminates with an embedded delamination. It is of particular interest to veryfy whether delamination growth cddurs with continuming deformation after buckling of composite laminates with an embedded delamination. Experiments are conducted for [0/sub 4///90/sub 8//0/sub 4/]/sub r/ laminates with delamination size in which local buckling mode governs buckling. Results show that delamination growth occurs in hgigher load after buckling and is accompanid by other damage mechanisms such as splitting. Also, it is found that transverse deformation before difurcation buckling is due to initial imperfection and structure such as plate with small bending stiffness is sensitive to that.

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.313-320
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• 2003

The governing equation of the post-buckling of shear-deformable uniform columns under a combined load consisting of a uniformly distributed axial load and a concentrated load at a free end was derived and the post-buckling analysis was investigated by using differential transformation. The loads were obtained for various end-slopes. The results obtained by the present method agree well with published results. In this paper, the differential transformation method was illustrated through its application to the non-linear differential equation of the post-buckling. It is expected that applications of the method to more challenging problems will are expected follow in future to ensue.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.407-421
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• 1998

The purpose of this paper is to provide and verify an analytical method, based on the spline finite strip method, which can be used to investigate the buckling mode and stress of thin-walled steel sections. Geometric imperfection and initial stress of plates and plate assemblies, which are resulted from various preloadings and may cause prebuckling deformations before buckling, are included in the analysis. Material nonlinearity and residual stress are also considered. It can be applied to sections with simple or non-simple boundary conditions and arbitrary loading. The method has been applied to investigate the buckling behavior of plates and plate assemblies which are subjected to compression with initial imperfections and residual stresses.

• Computational Structural Engineering
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• v.11 no.4
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• pp.155-168
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• 1998

보강된 판 및 쉘구조의 안정성 및 후좌굴을 포함하는 기하학적 비선형 해석을 수행하기 위하여, total Lagrangian formulation에 근거한 연속체의 증분평형방정식으로부터 변형된 쉘요소인 유한요소이론을 제시하였다. 쉘구조의 곡률이 불연속적으로 변하거나 쉘부재들이 유한한 각도로 만나는 보강된 판 및 쉘구조의 비선형 해석이 가능하도록 주부재와 보강재 간의 연결점에 대한 일반적인 변환관계를 제시하였으며 좌굴해석 및 기하학적 비선형해석의 경우에 해의 정확성 및 수렴성을 개선시키기 위하여 접선강도행렬 산정시 회전각의 2차항을 포함시켰다. 또한, shear locking 현상을 극복하기 위하여 감차적분을 적용하였고 쉘구조의 좌굴해석에서는 power method를 적용하여 해석의 효율을 높였으며, 후좌굴해석에서는 변위 및 하중증분법을 적절히 결합시켜 보강된 쉘구조의 후좌굴 거동추적이 용이하였다. 또한, 입력자료를 손쉽게 준비하고 좌굴모드 및 후좌굴거동을 효율적으로 분석하기 위하여 전, 후 처리 프로그램을 개발하였고 다양한 해석예제를 통하여 다른 문헌의 해석결과를 비교함으로써 본 연구에서 개발된 유한요소 해석프로그램의 타당성 및 정확성을 입증하였다.

• Journal of Korean Society of Steel Construction
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• v.17 no.2 s.75
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• pp.139-149
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• 2005

Post-local buckling behavior is a very important consideration in plastic and seismic design of steel structures. It describes the structural behavior up to the final collapse state. In order to assess the actual reliability of structures under severe repeated loading, such as strong earthquakes, it is necessary to evaluate the progressive cyclic deterioration of stiffness as well as the strength and energy dissipation capacity of the structures after local buckling happens. In this study, a simple analytical model developed for predicting post-local buckling behavior for cyclic and non-proportional loading histories, has been proposed. This analytical model uses the stress resultant model based on the two surface model. Analytical moment-curvature relationship using this model compare well with the experimental results in constant amplitude cycling, and linearized energy deterioration which is very important in seismic design can be predicted from the proposed model.