• 동력기계공학회지
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• 제22권1호
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• pp.25-33
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• 2018

The safety of structure was evaluated by taking into consideration the complex marine environmental conditions of the Lattice boom crane, which is widely used in offshore plants due to less influence by wind. CFX analysis was carried out to take into account the influence of wind speed, and the result was applied as a boundary condition to perform static analysis according to the luffing angles of $28^{\circ}$, $61^{\circ}$, and $80^{\circ}$ in the on board and off board, respectively. In addition, the Lattice Boom Crane is large slender structure, and the possibility of buckling is interpreted under three conditions where the biggest stress occurs. All conditions satisfied the safety requirements of the Classification Regulations. Also, as a result of the buckling analysis, the load less than the critical load was applied so buckling does not occur.

• 항공우주기술
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• 제9권1호
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• pp.9-16
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• 2010

본 연구에서는 이전에 구조시험[3]을 실시하였던 압축하중을 받는 샌드위치 패널 시편에 대한 구조 해석을 수행하였다. 구조 해석을 위해 세 가지 방식의 유한요소 모델링을 고려하였으며, 각각의 유한요소 모델을 이용해 선형좌굴해석과 비선형해석을 수행하였다. 이를 통해, 복합재 샌드위치 패널의 압축 좌굴 하중의 정확한 예측을 위해서는 면재는 쉘요소로 심재는 솔리드 요소로 모델링하는 것이 적절함을 확인하였다. 이것은 전체 샌드위치를 쉘요소로 하는 경우, 심재의 국부적인 crushing 효과와 심재의 전단 강성의 영향을 고려할 수 없기 때문이다. 만일 샌드위치 패널이 좌굴 하중 보다 면재의 재료 파손이 더 취약한 경우, 면재의 재료 파손 하중 및 파손 위치의 정확한 예측을 위해서는 샌드위치를 두께 방향으로 한 개의 쉘 요소로 모델링 하는 것이 적절하였다.

• Geomechanics and Engineering
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• 제28권4호
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• pp.335-346
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• 2022

Buckling failure is a typical slope instability mode that should be paid more attention to. It is difficult to provide systematic guidance for the monitoring and management of such slopes due to unclear mechanism. Here we examine buckling failure as the potential instability mode for a slope above a railway tunnel in southwest China. A comprehensive model test system was developed that can be used to conduct buckling failure experiments. The displacement, stress, and strain of the slope were monitored to document the evolution of buckling failure during the experiment. Monitoring data reveal the deformation and stress characteristics of the slope with different slipping mass thicknesses and under different top loads. The test results show that the slipping mass is the main subject of the top load and is the key object of monitoring. Displacement and stress precede buckling failure, so maybe useful predictors of impending failure. However, the response of the stress variation is earlier than displacement variation during the failure process. It is also necessary to monitor the bedrock near the slip face because its stress evolution plays an important role in the early prediction of instability. The position near the slope foot is most prone to buckling failure, so it should be closely monitored.

• 한국공간구조학회논문집
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• 제12권4호
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• pp.47-56
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• 2012

This paper describes the structural design and optimization of sinusoidally corrugated web girder by using EUROCODE (EN 1993-1-5). The optimum design methodology and characteristics of the optimal cross-section are discussed. We investigate a shear buckling and the concerned standards for corrugated web and explain the equations to obtain a critical stress according to buckling type. In order to perform optimization, we consider an objective function as minimum weight of the girder and use the constraint functions as slenderness ratio and stresses of flanges as well as corrugated web and deflection. Genetic Algorithm is adopted to search a global optimum solution for this mathematical model. For numerical example, the clamped girder under the concentrated load is considered, while the optimum cross-sectional area and design variables are analyzed. From the results of the adopted example, the optimum design program of the sinusoidally corrugated web girder is able to find the suitable solution which satisfied a condition subject to constraint functions. The optimum design shows the tendency to decrease the cross-sectional area with the yielding strength increase and increase the areas with load increase. Moreover, the corrugated web thickness shows a stable increase concerning the load.

• Steel and Composite Structures
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• 제17권1호
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• pp.1-19
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• 2014

Buckling and vibration characteristics of circular laminated plates under in-plane edge loads and resting on Winkler-type foundation are solved by the Ritz method. Inclusive numerical data are presented for the first three eigen-frequencies as a function of in-plane load for different classical edge conditions. Moreover, the effects of fiber orientation on the natural frequencies and critical buckling loads of laminated angle-ply plates with stacking sequence of $[({\beta}/-{\beta}/{\beta}/-{\beta})]_s$, are studied. Also, selected deformation mode shapes are illustrated. The correctness of results is established using finite element software as well as by comparison with the existing results in the literature.

• Advances in materials Research
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• 제7권1호
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• pp.1-16
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• 2018

Thermal bifurcation buckling behavior of fully clamped Euler-Bernoulli nanobeam built of a through thickness functionally graded material is explored for the first time in the present paper. The variation of material properties of the FG nanobeam are graded along the thickness by a power-law form. Temperature dependency of the material constituents is also taken into consideration. Eringen's nonlocal elasticity model is employed to define the small-scale effects and long-range connections between the particles. The stability equations of the thermally induced FG nanobeam are derived via the principal of the minimum total potential energy and solved analytically for clamped boundary conditions, which lead for more accurate results. Moreover, the obtained buckling loads of FG nanobeam are validated with those existing works. Parametric studies are performed to examine the influences of various parameters such as power-law exponent, small scale effects and beam thickness on the critical thermal buckling load of the temperature-dependent FG nanobeams.

• Advances in materials Research
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• 제5권3호
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• pp.141-169
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• 2016

In this paper, an efficient and simple refined theory is presented for buckling analysis of functionally graded plates. The theory, which has strong similarity with classical plate theory in many aspects, accounts for a quadratic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The mechanical properties of functionally graded material are assumed to vary according to a power law distribution of the volume fraction of the constituents. Governing equations are derived from the principle of minimum total potential energy. The closed-form solutions of rectangular plates are obtained. Comparison studies are performed to verify the validity of present results. The effects of loading conditions and variations of power of functionally graded material, modulus ratio, aspect ratio, and thickness ratio on the critical buckling load of functionally graded plates are investigated and discussed.

• Structural Engineering and Mechanics
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• 제6권2호
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• pp.161-172
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• 1998

Reinforced concrete beams possess variable flexural and torsional stiffnesses due to formation of cracks in the tension area along the beam. In order to check the stability of the beam, it is thus more appropriate to divide the beam into a finite number of segments for which mean stiffnesses and also bending moments are calculated. The stability analysis is further simplified, by using these mean values for each segment. In this paper, an algorithm for calculating the critical lateral buckling slenderness ratio for a definite load level, in a reinforced concrete beam without lateral support at the flanges, is presented. By using this ratio, the lateral buckling safety level of a slender beam may be checked or estimated.

• Structural Engineering and Mechanics
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• 제54권3호
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• pp.579-595
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• 2015

A general geometrically non-linear model for lateral-torsional buckling of thick and thin-walled FGM box beams is presented. In this model primary and secondary torsional warping and shear effects are taken into account. The coupled equilibrium equations obtained from Galerkin's method are derived and the corresponding tangent matrix is used to compute the critical moments. General expression is derived for the lateral-torsional buckling load of unshearable FGM beams. The results are validated by comparison with a 3D finite element simulation using the code ABAQUS. The influences of the geometrical characteristics and the shear effects on the buckling loads are demonstrated through several case studies.

• Structural Engineering and Mechanics
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• 제12권6호
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• pp.595-614
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• 2001

This paper studies the behaviour of a homogeneous cable in a horizontal rigid duct and loaded by an axial compressive force. This behaviour is characterized by spatial buckling modes, named sinusoidal and helical, due to friction and total or partial cable locking. The evaluation of critical buckling loads involved by drilling technology has been studied by many authors. This work presents a new formulation, taking the friction effects into account, for the transmission of the axial load during the postbuckling process. New analytical expressions of pitches in both buckling cases are also given. A life-sized bench is presented, which permits to study the laying of optical fiber cables by squeezing them into an underground duct. Finally, analytical solutions are compared with experimental tests and finite element simulations.