• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.399-408
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• 2000

IN analyzing earthquake response of structures important focus is on their diaplacements and shear forces. However seismic technology of passive energy dissipation makes focus on the seismic energy distribution of structures. The passive dampers enhance the capability of energy dissipation by their hysteretic behavior thus preventing the structural plastic deformation. In this paper the building structure with an active controller is analyzed with the view of earthquake energy distribution under elastic and plastic behaviors. The active control makes an effect of increasing damping capability which absorbs most of the earthquake input energy. Finally the different active gains resulting from the plastic deformation are applied to the active analysis and control forces and earthquake energy response are compared.

• Structural Engineering and Mechanics
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• v.35 no.1
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• pp.67-82
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• 2010

The beam string structure (BSS) has been widely applied in large span roof structures, while no analytical solutions of BSS were derived for it in the existing literature. In the first part of this paper, calculation formulas of displacement and internal forces were obtained by the Ritz-method for the most commonly used arc-shaped BSS under the vertical uniformly distributed load and the prestressing force. Then, the failure mode of BSS was proposed based on the static equilibrium. On condition the structural stability was reliable, BSS under the uniformly distributed load would fail by tensile strength failure of the string, and the beam remained in the elastic or semi-plastic range. On this basis, the limit load of BSS was given in virtue of the elastic solutions. In order to verify the linear elastic and limit state solutions proposed in this paper, three BSS modal were tested and the corresponding elastoplastic large deformation analysis was performed by the ANSYS program. The proposed failure mode of BSS was proved to be correct, and the analytical results for the linear elastic and limit state were in good agreement with the experimental and FEM results.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.195-204
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• 2018

Based on theories of rock mechanics, rock fragmentation, mechanics of elasto-plasticity, and energy dissipation etc., a method is presented for evaluating the rock fragmentation efficiency by using plastic energy dissipation ratio as an index. Using the presented method, the fragmentation efficiency of rocks with different strengths (corresponding to soft, intermediately hard and hard ones) under indentation is analyzed and compared. The theoretical and numerical simulation analyses are then combined with experimental results to systematically reveal the fragmentation mechanism of rocks under indentation of indenter. The results indicate that the fragmentation efficiency of rocks is higher when the plastic energy dissipation ratio is lower, and hence the drilling efficiency is higher. For the rocks with higher hardness and brittleness, the plastic energy dissipation ratio of the rocks at crush is lower. For rocks with lower hardness and brittleness (such as sandstone), most of the work done by the indenter to the rocks is transferred to the elastic and plastic energy of the rocks. However, most of such work is transferred to the elastic energy when the hardness and the brittleness of the rocks are higher. The plastic deformation is small and little energy is dissipated for brittle crush, and the elastic energy is mainly transferred to the kinetic energy of the rock fragment. The plastic energy ratio is proved to produce more accurate assessment on the fragmentation efficiency of rocks, and the presented method can provide a theoretical basis for the optimization of drill bit and selection of well drilling as well as for the selection of the rock fragmentation ways.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.1
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• pp.89-95
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• 1989

In this study, it is attempted to examine (1) the residual deformation and elastic deformation induced from the repeated loads (up to the maximum of 100,000 times) on fully compacted soil specimen, the relation between stress and strain by performing the unconfined compressive test, after repeated loads and (2) the effect of water content, dry density, number of cycle, repeated loads, etc. on the effect of the stress-strain relation. The rate of deformation caused by repeated loads greatly depends on to the condition whether the water content is above or below the plastic limit. It is possible to estimate the initial tangent modulus of soil by means of modulus of elastic deformation obtained by putting repeated loads on the clay soil.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.45-54
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• 2004

Recently, as steel structures become higher and more long-spanned, application of high-strength steels is increasing gradually. For seismic design of steel structures using high-strength steels(POSTEN60, POSTEN80), analytical method, can describe the large deformation and inelastic cyclic behavior generated by non-proportional cyclic loading, are required. In this paper, cyclic plasticity model was proposed by results of monotonic loading tests ant cyclic loading tests. Three-dimensional finite element analysis is developed by using proposed model and finite deformation theory and verified as compare with experiment result. Using 3-dimensional elastic-plastic finite deformation analysis, seismic analysis of high-strength steel pipe-section piers are carried out. Also, seismic performance of high-strength steel pipe-section piers in parameter of diameter-thickness ratio was clarified.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.261-266
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• 1998

This paper presents a numerical simulation of the failure behaviour for the pipeline which has external corroded parts along the axis. The numerical study for the pipeline failure analysis is based on an FEM with an elastic-plastic and large-deformation. The predicted failure assessments for the simulated corrosion defects are compared with ANSI/ASME B31G code and a modified B31G method.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.409-414
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• 2005

It is difficult to apply the Hertz theory to the wheel-rail contact problem which has the complicated geometric form and plastic deformation. Therefore, we perform the elastic-plastic FE analysis and compare the results with those of Hertz theory. Kalker's simplified theory of rolling contact is used to discretize the contact patches and calculate local traction and slip. The wear volumes are calculated using Archard wear equation.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.401-419
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• 1997

In this paper the kinematics of damage for finite strain, elasto-plastic deformation is introduced using the fourth-order damage effect tensor through the concept of the effective stress within the framework of continuum damage mechanics. In the absence of the kinematic description of damage deformation leads one to adopt one of the following two different hypotheses for the small deformation problems. One uses either the hypothesis of strain equivalence or the hypotheses of energy equivalence in order to characterize the damage of the material. The proposed approach in this work provides a general description of kinematics of damage applicable to finite strains. This is accomplished by directly considering the kinematics of the deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain equivalence approaches. In this work, the damage is described kinematically in both the elastic domain and plastic domain using the fourth order damage effect tensor which is a function of the second-order damage tensor. The damage effect tensor is explicitly characterized in terms of a kinematic measurure of damage through a second-order damage tensor. Two kinds of second-order damage tensor representations are used in this work with respect to two reference configurations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2223-2233
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• 1993

An engineering method is suggested to calculate the applied load versus crack extension in the elastic-plastic fracture. The condition for an increment of crack extension is set by a critical increment of crack-up opening displacement(CTOD). The ratio of the CTOD increment to the incremental crack extention is a critical crack-tip opening angle(CTOA), assumed to be constant for a material of a given thickness. The Dugdale model of crack-tip deformation in an infinite plate is applied to the method, and a complete solution for crack extension and crack instability is obtained. For finite-size specimens of arbitrary geometry in general yielding, an approximate generalization of the Dugdale model is suggested so that the approximation approaches the small-scale yielding solution in a low applied load and the finite-element solution in a large applied load. Maximum load is calculated so that an applied load attains either a limit load on an unbroken ligament or a peak load during crack extension. The proposed method was applied to three-point bend specimens of a carbon steel SM45C in various sizes. Reasonable agreements are found between calculated maximum loads and experimental failure loads. Therefore, the method can be a viable alternative to the J-R curve approach in the elastic-plastic fracture analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.131-138
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• 2002

This paper provides the fully plastic J solutions for circumferential cracked pipes with inner, semi- elliptical surface cracks, subject to internal pressure and global bending. Solutions are given in the form of two different approaches, the GEF/EPRl approach and the reference stress approach. For the GE/EPRl approach, the plastic influence functions for fully plastic J are tabulated based on extensive 3-D FE calculations using the Ramberg-Osgood (R-O) materials, covering a wide range of pipe and crack geometries. The developed GEf/EPRl-type fully plastic J estimation equations are then re-formulated using the concept of the reference stress approach for wider applications. Based on the FE results, optimized reference load solutions for the definition of the reference stress are found for internal pressure and for global bending. Advantages of the reference stress based approach over the GE/EPRl-type approach are fully discussed. Validation of the proposed reference stress based J estimation equations will be given in Part II, based on 3-D elastic-plastic or elastic creep FE results using typical tensile properties of stainless steels and generalized creep- deformation behaviours.