• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.2
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• pp.140-147
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• 1998

Since a structure carries out its given functions and purposes while it is always resisting against the external load, the capacity of the resistance in the structure within the range that will not collapse the structure itself becomes the important factor in the design of the structures. Therefore, many suggestions were proposed and noted for determining method of the collapse load. Some of the methods from the suggestions have been commonly used due to the considerations on their distinctive advantages such as the compactness of the conceptions and the convenience in the computation. However, in case when the variation becomes huge in the materials and load, the results would carry(have or contain) many uncertain elements. On the other hand, load incremental method which regards the characteristics of the probability must be more attainable method even though it might complicate the calculation. This study intends to develop a finite element model that uses the probabilistic load incremental method to estimate the collapse load, and also to compare the result of the analysis with the linear load incremental method and Turkstra's Rule.

• Wind and Structures
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• v.31 no.6
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• pp.509-522
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• 2020

Wind load is the principal cause for a large number of the collapse of transmission lines around the world. The transmission line is traditionally designed for wind load according to a linear equivalent method, in which dynamic effects of wind are not appropriately included. Therefore, in the present study, incremental dynamic analysis is utilized to investigate the stability behavior of a 400 kV transmission line under wind load. In that case, the effects of vibration of cables and aerodynamic damping of cables were considered on the stability behavior of the transmission line. Superposition of the harmonic waves method was used to calculate the wind load. The corresponding wind speed to the beginning of the transmission line collapse was determined by incremental dynamic analysis. Also, the effect of the yawed wind was studied to determine the critical attack angle by the incremental dynamic method. The results show the collapse mechanisms of the transmission line and the maximum supportable wind speed, which is predicted 6m/s less than the design wind speed of the studied transmission line. Based on the numerical modeling results, a retrofitting method has been proposed to prevent failure of the tower members under design wind speed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.341-344
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• 2009

Large load is required in forging of large-scale components, which becomes a critical restriction in practice. However, the load can be greatly reduced by adopting incremental forging technologies. In the present study, two methods of incremental forging were investigated for the purpose of reducing the load required. One was to use nine strokes with a flat die and the other was to use three strokes with a curved die. The die moves vertically in the former while it moves vertically as well as rolls horizontally in the latter. Deformation of the slab in each case was analyzed by rigid-plastic finite element method and as a result, variations of load and distributions of effective strain were predicted.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.381-383
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• 2003

The authors have developed a solution method based on the incremental algorithm. The optimal load balance between feeders is found through the incremental algorithm with allowing the loop configuration. Therefore loops can be configured in the resulting configuration, and then we must eliminate all loops to satisfy radiality of distribution system because the distribution system is operated under radial status. But the optimal load balance through incremental algorithm is deteriorated when the loops are eliminated. In this paper, authors propose a new method which is to improve the searching procedure of path in the incremental algorithm, that is, so as not to make loop in the path configuration.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1931-1942
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• 1997

A new load/displacement parameter method is developed for the cases that loads are applied to one or more points, and displacements of a structure are controlled at one or more points sinultaneously. The procedure exploits a generalized Riks method, which utilizes load/displacement parameters as scaling factors in order to analyze the post-buckling phenomena including snap-through or snap-back. A convergence characteristic is improved by employing new relaxation factors in incremental displacement parameter, particularly at the region where exhibits severe numerical instability. The improved performance is illustrated by means of numerical example.

• Structural Engineering and Mechanics
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• v.19 no.2
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• pp.153-172
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• 2005

A new load/displacement parameter method is proposed for the simultaneous control of applied loads and structural displacements at one or more points. The procedure is based on a generalized Riks' method, which utilizes load/displacement parameters as scaling factors to analyze post-buckling phenomena including snap-through or snap-back. The convergence characteristics are improved by employing new relaxation factors through an incremental displacement parameter, particularly in a region that exhibits severe numerical instability. The improved performance is illustrated by means of a numerical example.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.1
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• pp.21-30
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• 1985

This paper deals whth the buckling as well as postbuckling analysis of axisymmertric shells taking the initial deflection effects into account. Incremental equilibrium equations, based on the principle of virtual work, were derived by the finite element method, the successive step-by-step Newton-Raphson iterative technique was adopted. To define the transition pattern of postbuckling behavior from the prebuckling state more accurately, a simple solution method was developed, i.e. the critical load was calculated by the load extrapolation method with the determinant of tangent stiffness matrix and the equilibrium configuration in the immediate postbuckling stage was obtained by perturbation scheme and eigenvalue analysis. Degenerated isoparametric shell elements were used to analyse the axisymmetric shell of revolution. And by the method developed in this paper, the computer program applicable to the nonlinear analysis of both thin and moderately thick shells was constructed. To verify the capabilities and accuracies of the present solution method, the computed results were compared with the results of analytical solutions. These results coincided fairly well in both the small deflection and large deflection ranges. Various numerical analyses were done to show the effect of initial deflection and shape of shells on buckling load and postbuckling behavior. Futhermore, corrected directions of applied loads at every increment steps were used to determine the actual effects of large deflection in non-conservative load systems such as hydrostatic pressure load. The following conclusions can be obtained. (1) The method described in this paper was found to be both economic and effective in calculating buckling load and postbuckling behavior of shell structure. (2) Buckling and postbuckling behavior of spherical caps is critically dependent upon their geometric configuration, i.e. the shape of spherical cap and quantities of the initial deflection. (3) In the analysis of large deflection problems of shells by the incremental method, corrections of the applied load directions are needed at every incremental step to compensate the follower force effects.

• Transactions of Materials Processing
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• v.18 no.7
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• pp.513-518
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• 2009

Large load is required in forging of large-scale components which becomes a critical restriction in practice. In the present study, two methods of incremental forging were investigated for the purpose of reducing the load required for forging of large and thick plates. The forging was applied primarily to obtain fine grains by imposing large amount of plastic deformation to the plates. One was to use nine strokes with a flat die and the other was to use three strokes with a curved die. The die moves vertically in the former while it moves vertically as well as rolls horizontally in the latter. Deformation of the slab in each case was analyzed by rigid-plastic finite element method and as a result, variations of load and slab holding force, and distributions of effective strain and thickness were predicted.

• Structural Engineering and Mechanics
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• v.13 no.1
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• pp.35-52
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• 2002

It was shown in the previous study (Lee and Bertero 1993) that incremental collapse can lead to the exhaustion of the plastic rotation capacity at critical regions in a structure when subjected to the number of load cycles and load intensities as expected during maximum credible earthquakes and that this type of collapse can be predicted using the shakedown analysis technique. In this study, a minimum-weight design methodology, which takes into account not only the prevention of this incremental collapse but also the requirements of the serviceability limit states, is proposed by using the shakedown analysis technique and a nonlinear programming algorithm (gradient projection method).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.107-115
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• 1985

For the finite deflection analysis of plates with initial deflections subjected to uniaxial compression, the formulation of incremental finite strip method is made and has been incorporated into a computer program. A new in plane displacement function varying along the load: direction has been derived from the out-of-plane displacement function by considering the curvature of a plate. Either incremental load type analysis or incremental displacement type analysis may be selected to solve incremental equibrium equations in the program. The following results have been obtained: 1. Incremental displacement type analysis is superior to incremental load type analysis in that the former converges more rapidly than the latter. 2. The finite strip method using the new displacement function gives as accurate results as analytical method and other finite element methods.