• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.7-14
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• 2001

구조물 하중에 의한 점성토 지반의 침하량을 보다 정확하게 평가하기 위해서는 지반 내의 흙요소가 경험하는 실제적인 응력경로와 이에 따른 변형양상이 적절하게 고려되어야만 한다. 따라서 본 연구에서는 축대칭 조건의 다양한 응력경로를 따라 발생하는 정규압밀 점성토의 변형 거동을 고찰한 기존의 실험적 연구결과를 바탕으로 응력경로법에 근거한 보다 간편하고 합리적인 침하량 평가기법을 제시하였다. 또한 본 연구에서는 제시된 평가기법을 기존의 1차원적인 침하량 평가기법들과 함께 실제와 유사한 조건을 가지는 가상지반의 침하량 산정에 적용해 보았으며, 동일한 조건에 대해 소성모델(MCC 모델)과 혼합압밀이론에 바탕을 둔 유한요소해석을 실시하였다. 그리고 이를 통해 얻어진 결과들을 비교.분석함으로써 기존 평가기법들의 문제점과 한계를 명확히 제시하였으며, 응력증분 평가방법이 침하량 평가에 미치는 영향을 분석하였다.

• Computational Structural Engineering
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• v.7 no.4
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• pp.113-118
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• 1994

The purpose of this study is elastic plastic finite element analysis for standard fracture toughness specimens. The principles of elastic-plastic fracture mechanics are shortly summarized and the special requirements for computational tools are derived. Possibilities to model the crack tip singularities are mentioned. The relevant fracture parameters like J-Integral and COD and their correlation are evaluated from elastic plastic finite element calculations of standard fracture toughnes specimens. The size and form of the plastic zone are shown. The comparion between experiment and caculation is discussed as well as the application of the limit load analysis.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.91-101
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• 2011

In this study, a new design method of Pile-Bent structure considering plastic hinge was proposed on the basis of the beam-column model. To obtain the detailed informations, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Base on this study, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio ($D_c/D_p$) and normalized lateral cracking load ratio ($F/F_{Dc=Dp}$). Moreover, through comparisons with field cases to find out in-depth limit in which minimum concrete-steel ratio could be applied, in-depth limits ($L_{As=0.4%}$) normalized by the pile length ($L_p$) proportionally decrease as the pile length ($L_p/D_p$)increases up to $L_p/D_p=17.5$, and beyond that in-depth limit converges to a constant value (${\simeq}0.3$).

• Computational Structural Engineering
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• v.4 no.3
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• pp.79-88
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• 1991

The procedure of the elastic response spectrum method which is used in the codes of many countries involves the computation of a static horizontal substitute loading resulting from the earthquake. The substitute loading is divided by a behavioral factor in order to take energy dissipation due to the real nonlinear structural behavior and damping effects ect. into account. The behavioral factors widely used in many countries are based not on the exact calculation but only on the empirical data. In order to determine the behavioral factors analytically, it is necessary to define the limit state of structures as a first step. In this work, the methods of the determination of limit state for the steel structures are discussed in the geometric, serviceabile and material apsects, and the behavioral factors for the three types of structures are calculated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4216-4222
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• 2011

In this study the inelastic behavior of the existing school buildings with infilled masonry walls is analysed by pushover method. The shear stiffness and strength of masonry wall is calculated from the prior experimets and verified by inelastic analysis. The height of infilled masonry wall affects the structural behavior. The higher the masonry wall height, the higher the initial shear stiffness and strength of masonry wall. As the cracks are developed, the strength of masonry wall is much decreased. The proposed inelastic analysis method shows similar results with the experiments and can be used as inelastic analysis model of reinforced concrete buildings with infilled masonry walls.

• Geotechnical Engineering
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• v.10 no.2
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• pp.25-40
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• 1994

In order to investigate behavior of lateral flow by plasticity of soils and construction control due to it, in the case of unsymmetrical surcharge load on the soft soils, we examine the existing theoretical background, and compared and analysed the experimental results by model test. After model test fabricated by model test apparatus, which made full remolding samples of soft soils, we observed the state of behavior for deformation with increasing load step to constant time interval. The critical surcharge and ultimate capacity showed tendency to approach to the proposed value of Jaky and Meyerhof, and the lateral flow pressure of which the maximum value was acted on the depth calculated by z/H=0.26+1.71cu and one third value of the maximum lateral flow pressure acted on the ground surface, approach the trapezoid distribution And maximum lateral flow pressure will be calculated by proposed equation of Hong or simple equation which($\alpha=0.4$) the flow pressure coefficient . of proposed equation by Tschebotarioff exchanged to($\alpha=K_0$) . Basides, the failure surcharge by [(q/$y_m$)-q] and [$S_y-(y_m/S_y)$] showed the smaller than ultimate bearing capacity, especially failure criteria line of control diagram of [$S_y(y_m/S_y)$] will be calculated by following equation. $S_y.=3.15exp[-0.58(y_m/S_y)$

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.391-402
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• 1994

One of the most important design concept for reinforced concrete structures is to achieve a ductile failure mode, and also moment redistribution for economic design is possible in case that adequate ductility is provided. Flexural ductility index is, therefore, used as a reference for possibility of moment redistribution as well as for prediction of flexural behavior of designed R.C. structures. Ductility index equations, however, provide approximate values due to the linear concrete compressive stress assumption at the tension steel yielding state. Theoretically more exact ductility index is calculated by a numerical analysis with the realistic stress-strain curves for concrete and steel to be compared with the result from tire ductility index equations. Variation of ductility index for the selected variables and the reasonable maximum tension steel ratio for doubly reinforced section are investigated. A moment-curvature curve model is also proposed for future research on moment redistribution.

• Journal of the Korea Concrete Institute
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• v.18 no.4 s.94
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• pp.469-477
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• 2006

Models to predict the ultimate strength of simply supported or continuous deep beams with web openings are proposed. The derived equations are based on upper-bound theorem. The concrete is assumed as a perfectly plastic material obeying the modified Coulomb failure criteria with zero tension cutoff. Reinforcing bar is considered as elastic-perfectly plastic material and its stress is calculated from the limiting principal compressive strain of concrete. The governing failure mechanisms based on test results are idealized as rigid moving blocks separated by a hyperbolic yield line. The effective compressive strength of concrete is calculated from the formula proposed by Vecchio and Collins. Comparisons with existing test results are performed, and they show good agreement.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.301-310
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• 2006

If arches are braced by lateral restraints, the ultimate strength of arches is determined by in-plane buckling and plastic bending collapse. This paper is conducted to investigate the in-plane nonlinear elastic and inelastic buckling behavior and the strength of fixed parabolic arches in uniform compresion, as well as to study arch behaviors against non-uniform in-plane compression and bending. As shown by the results, the limit slenderness ratio is suggested to classify the bucklingmode. Buckling strength of fixed parabolic arches under uniform compresion are evaluated using buckling curve for a straight column. Finally, an interaction e quation for arches under combined axial compresion and bending action is proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.269-278
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• 2006

This paper proposes slip line fields for bending of unequally notched specimens in plane strain that have a sharp crack in one side and a sharp V-notch in the other side. Depending on the back angle, two slip line fields are proposed, from which the limit moment and crack tip stress fields are obtained as a function of the back angle. Excellent agreement between slip line field solutions with those from detailed finite element limit analysis based on non-hardening plasticity provides confidence in the proposed slip line fields. One interesting point is that, for the unequally notched specimen, the difference between the crack tip triaxial stress for tension and that for bending increases significantly with increasing the back angle. This suggests that such a specimen could be potentially useful to investigate the crack tip constraint effect on fracture toughness of materials. In this respect, the possibility of designing a new toughness testing specimen with varying crack tip constraint is discussed.