• Architectural research
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• 제15권1호
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• pp.35-42
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• 2013

A study on the free vibration and linear buckling analyses of thick plates is described in this article. In order to determine the natural frequencies and buckling loads of plates, a plate element is developed by using isogeometric approach. The Non-uniform B-spline surface (NURBS) is used to represent both plate geometry and the unknown displacement field of plate. All terms required in isogeometric formulation are consistently derived by NURBS definition. The capability of the present plate element is demonstrated by using several numerical examples. From numerical results, it is found to be that the present isogeometric element can predict accurate natural frequencies and buckling loads of plates.

• Architectural research
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• 제18권3호
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• pp.113-120
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• 2016

The stability and resistance of the plates under in-plane loading is crucial in the design of structures. For the assessment of structural stability, it is necessarily required to have accurate finite element technologies. Therefore, the enhanced 9-node plate (Q9-ANS) element is introduced for the linear buckling analysis of plate where the critical buckling load has to be determined. The Q9-ANS is developed with the Reissner-Mindlin (RM) assumptions which consider transverse shear deformation of the plate. Assumed shear strain is used to alleviate the shear locking phenomenon. Numerical examples are carried out to verify the performance of the Q9-ANS element in calculation of critical buckling load of the plates.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.187-194
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• 1999

Laminated rubber bearings are widely used as a key component in seismic isolation of structural systems subjected to earthquake loadings. The combination of rubber layers and reinforcing steel shims makes the bearings conditionally unstable similar to buckling of ordinary columns. The shear flexibility of these short columns can lead to relatively low buckling Toads which may be further reduced when high shear strains are simultaneously imposed As an analytical approach, the area reduction formula has been proposed to account for the reduction in buckling load due to shear, but the degree of conservatism is unknown. In order to complement analytical approaches, a non-linear finite element analysis can be used. In this paper, a numerical study which aims at determining the effect of high shear strain on the critical load of elastomeric bearings is presented. From the load-displacement curve at each specified shear displacement, the buckling load can be obtained using the Southwell procedures. The results obtained are then compared against the theoretical predictions in order to examine the validity and the conservatism of the theoretical formulas.

• Advances in Computational Design
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• 제5권3호
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• pp.209-231
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• 2020

In order to evaluate the performance of three heuristic optimization algorithms, namely, simulated annealing (SA), genetic algorithm (GA) and particle swarm optimization (PSO) for optimal stacking sequence of laminated composite plates with respect to critical buckling load and non-dimensional natural frequencies, a multi-objective optimization procedure is developed using the weighted summation method. Classical lamination theory and first order shear deformation theory are employed for critical buckling load and natural frequency computations respectively. The analytical critical buckling load and finite element calculation schemes for natural frequencies are validated through the results obtained from literature. The comparative study takes into consideration solution and computational time parameters of the three algorithms in the statistical evaluation scheme. The results indicate that particle swarm optimization (PSO) considerably outperforms the remaining two methods for the special problem considered in the study.

• Advances in concrete construction
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• 제9권4호
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• pp.397-406
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• 2020

The present article deals with post-buckling of geometrically imperfect concrete plates reinforced by graphene oxide powder (GOP) based on general higher order plate model. GOP distributions are considered as uniform and linear models. Utilizing a shear deformable plate model having five field components, it is feasible to verify transverse shear impacts with no inclusion of correction factor. The nonlinear governing equations have been solved via an analytical trend for deriving post-buckling load-deflection relations of the GOP-reinforced plate. Derived findings demonstrate the significance of GOP distributions, geometric imperfectness, foundation factors, material compositions and geometrical factors on post-buckling properties of reinforced concrete plates.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2005년도 춘계학술발표회 및 정기총회 2권1호(통권2호)
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• pp.147-153
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• 2005

The single layer latticed dome is very sensitive on the slenderness ratio and half open angle of the elements, load condition, and the connection type because it is originazed by a lot of thin elements, so we have to use the geometrically nonlinear buckling load when the buckling of the structures is analyzed. But, it is very difficult to design the single layer latticed domes considered all conditions. Therefore the purpose of this paper is to propose the appropriate design method of the single layer latticed dome considered the geometrically nonlinear buckling load in base of the linear buckling load by the eigenvalue analysis.

• 한국농공학회지
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• 제36권2호
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• pp.56-66
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• 1994

Numerical methods are developed to obtain the buckling loads and to analyze the postbuckling behavior of the tapered steel piles. The nondimensional differential equations governing the elastica of the buckled piles are derived by the third order theory and solved numerically. The Runge-Kutta method is used to solve the differential equations, and the bisection method is used to obtain the buckling loads and the reaction moments of the clamped ends. Both the linear and stepped taper of the steel piles are considered as the variable crosssection in the differential equations. As the numerical results, the equilibrium paths, the buckling loads vs. section ratio curves and the typical elastica and the bending moment diagrams of the buckled piles are presented in figures. Experimental studies that complement the theoretical results are presented. It is expected that the numerical methods developed in this study for calculating the buckling loads and analyzing the postbuckling behavior of the steel piles are used in the structural and foundation engineering.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.395-402
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• 1999

This paper discusses the theoretical researches subject to elastic buckling problems of the structures. The purpose is to ensure the characteristic of buckling be true by arc-length method and the finite element method. The difficulties in processes calculating the equilibrium curve after buckling is to get the equilibrium owe near singular point at which the determinant of stiffness matrix is zero. The purpose of the load-displacement curve is to determine the buckling load of the structure, and further to get the information about the characteristic after buckling. Here, this paper expresses the incremental solution at particular point by the linear combination of both homogeneous mode and particular mode, then uses the method which gets the unknown parameter including this function, through trial-and-error method including modified N-R convergence process. Finally, this paper describes the multiple bifurcation of truss dome as the numerical examples according to this algorithm.

• Structural Engineering and Mechanics
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• 제24권3호
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• pp.355-374
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• 2006

Thin walled steel bridge-piers/columns are vulnerable to damage, when subjected to earthquake excitations. Local buckling, global buckling or interaction between local and global buckling usually is the cause of this damage, which results in significant strength reduction of the member. In this study new innovative design concepts, "thin-walled corrugated steel columns" and "thin-walled cellular steel columns" are presented, which allow the column to undergo large plastic deformations without significant strength reduction; hence dissipate energy under cyclic loading. It is shown that, compared with the conventional designs, circular and stiffened box sections, these new innovative concepts might results in cost-effective designs, with improved buckling and ductility properties. Using a finite element model, that takes the non-linear material properties into consideration, it is shown that the corrugations will act like longitudinal stiffeners that are supporting each other, thus improving the buckling behavior and allowing for reduction of the overall wall thickness of the column.

• Advances in nano research
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• 제4권4호
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• pp.309-326
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• 2016

The buckling response of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak's medium is presented. The nonlocal first-order shear deformation elasticity theory is used for this purpose. The visco-Pasternak's medium is considered by adding the damping effect to the usual foundation model which characterized by the linear Winkler's modulus and Pasternak's (shear) foundation modulus. The SLGS be subjected to distributive compressive in-plane edge forces per unit length. The governing equilibrium equations are obtained and solved for getting the critical buckling loads of simply-supported SLGSs. The effects of many parameters like nonlocal parameter, aspect ratio, Winkler-Pasternak's foundation, damping coefficient, and mode numbers on the buckling analysis of the SLGSs are investigated in detail. The present results are compared with the corresponding available in the literature. Additional results are tabulated and plotted for sensing the effect of all used parameters and to investigate the visco-Pasternak's parameters for future comparisons.