• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.23-31
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• 1992

In this study, Behavior of Eccentrically Loaded Restrained Concrete Slender Columns are investigated the continuation. The paper is : nonlinear constitutive relations of reinforced concrete columns are formulated, the multivariable nonlinear equation formulated in this study is solved by the incremental iterative method, the solution scheme is suitable for computer application, the proposed method bas been compared with the numerical examples and other research results and is shown to be in good agreement Accordingly, the objectives of this investigation are to use the method developed to conduct a parametric study of the different variable (Rotational Restraints,Ratio of End Restraints. End Eccentricity, Ratio of End Eccentricities,Lateral Restraint, Concrete Strength, Ratio of Reinforcement. Yield Point of Reinforcement) influencing the behavior and the ultimate strength for columns. Chosen values for different parameters and their variations are based on values encountered in practice and on results of other analylitical studies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.83-88
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• 2013

Progressive collapse is a chain reaction of failures propagating throughout a portion of a structure that is disproportionate to the original local failure. When column members are subjected to unexpected load (compression load), they will buckle if the applied load is greater than the critical load that induces buckling. The post-buckling strength of the columns will decrease rapidly, but if there is enough residual strength, the members will absorb the potential energy generated by the impact load to prevent progressive collapse. Thus, it is necessary to identify the relationship of the load-deformation of a column member in the progressive collapse of a structure up to final collapse. In this study, we carried out nonlinear FEM analysis and based on deflection theory, we investigated the load-deformation relationship of H-section steel columns when both ends were fixed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.11-24
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• 1990

The effect of end restraints for adjoining members is the different variables influencing the column ultimate strength and the behavior. The propose of this study is to analyze eccentrically loaded reinforced concrete columns with the end restraind effect having rectangular cross-section and general boundary conditions. Accordingly, this investigation are to construct a typical analytical model of the reinforced concrete columns with general end boundary conditions. The mechanical components of the analytical model are to be rationally defined the actual behavior as possible, and the different variables influencing the behavior and the ultimate strength of the reinforced concrete columns are investigated by using a parametric study.

• Computational Structural Engineering
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• v.4 no.1
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• pp.121-132
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• 1991

The purpose of this study is to analyze concentrically loaded reinforced concrete columns with the restrained effect having rectangular cross-section and general boundary conditions. Accordingly, this investigation is to construct a typical analytical model of the reinforced concrete columns with general boundary conditions. The mechanical components of the analytical model are to be rationally defined so as to model the actual behavior as closely as possible, and the ultimate strength of the reinforced concrete columns are investigated by end restrained effect.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.441-450
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• 2010

This is a preliminary study on the development of precast beam-column joints for dry construction methodology. Precast beam column joints with thru-connectors (BCJ_TC) using high strength bars or PS strands were developed and their seismic performance including strength degradation, stiffness degradation and energy dissipation capacity was experimentally evaluated. Test results showed that compressive failures at the end blocks of PC beam members occurred dominantly while PC columns including panel zones were free from any damage. However, the connections confined with CFRP at the end block showed much improved seismic performance than that of the unconfined connections. Connections with neoprene pad fillers between beam and column interfaces were better than the other connections in all the seismic performances except initial stiffness. To improve the seismic performances of BCJ_TC, compressive strength of the concrete at the end block need to be increased to compensate for the additional compressive stresses due to unbonded connectors and deformation of connectors should be controlled respectively.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.1-10
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• 2012

This paper presents an experimental result and suggests the confinement effect of headed cross tie in reinforced concrete(RC) columns subjected to cycling horizontal loads under constant axial load. Five RC columns specimens were manufactured, taking confined type of transverse reinforcement, whether or not using cross tie, end detail of cross tie (hooked or headed), and axial stress in column as major variables, Cyclic horizontal load applied to the columns under constant axial stress and the effect of cross tie to structural capacity of column was evaluated from the test. The column without cross tie failed showing bending deformation of hoop with crack in core concrete at low horizontal load while the column with cross tie showed quite improved strength and ductility by suppressing bending deformation of hoop as well as buckling of longitudinal bar at once even after crack in core concrete. At high lateral displacement, the column with hooked cross tie showed the failure pattern loosing the confining force of cross tie since the $90^{\circ}$ hooked part of cross tie was stretched out and the cracked core concrete lumps were came off. However, the column with headed cross tie showed very stable behavior since the head of cross tie effectively confined the hoop and longitudinal bars even at high lateral displacement.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.1025-1032
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• 2005

This paper presents experimental and analytical studies on long-term behavior of square CFT columns with diaphragm. In order to investigate the effect of the diaphragm on the long~term behavior, experiments for six specimens with two diaphragms and three different column length, and three-dimensional finite element analysis for each specimen have been performed. The finite element models considering the interface behavior between the steel tube and the inner concrete were verified from comparison of the test results with the analysis results. From the test and the analysis results, the following conclusions were obtained. The confinement effect created by the diaphragm does not depends on column length and influences only a part of the whole column that is from the end to the depth which is the same to the width of the column. The shortening of the column with diaphragm which covers more than a half of the cross sectional area of the inner concrete is the same as that of the column under a load applied on the steel tube and the entire section of the inner concrete.

• Magazine of the Korea Concrete Institute
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• v.7 no.5
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• pp.133-144
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• 1995

This study investigated to the properties of structural behaviors through a series of experiment with the key parameter, such as diameter-to-thickness(D/t) ratio, selenderness ratio of steel t~ube and strength of concrete under loading condition simple confined concrete by steel tube as a fundmental study on adaptability with structural members in high-rise building. The obtained results are sumnarised as follow. (1) The fracture mode of confined concrete was presented digonal tension fracture in the direction of $45^{\circ}$ with compression failure at the end of specimen in stub column, but the fracture mode of long column was assumed an aspect of bending fracture transversely. (2) The deformation capacity and ductility effect was increased by confine steel tube for concrete. (3) 'The emprical formula to predict the ultimate capacity of confined concrete by steel tube and concrete filled steel tube column using restraint of concrete considered D / t ratio, selenderness ratio of steel tube anti strength of' concrete were proposed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.220-227
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• 2005

최근에 수행된 철골모멘트 접합부의 실험 및 해석결과에 의하면, 기둥으로 각형강관을 가진 접합부가 H형강을 기둥으로 사용하는 접합부에 실험체에 비해서 조기에 스캘럽 단부에서 취성파단이 발생하는 열등한 변형능력을 나타냈다. 이는 각형강관 기둥의 면외변형에 따른 보 웨브의 모멘트 전달효율의 저하, 스캘럽이 가지는 노치효과 및 합성보의 구속효과가 주요원인으로 밝혀졌다. 실험결과는 또한 개선된 수평스티프너로 하부 플랜지를 보강한 실험체는 우수한 변형능력을 가짐을 보였다. 본 연구에서는 이러한 영향을 고려하여, 다양한 수평스티프너로 보강된 접합부에 관한 유한요소해석을 실시하였다. 해석결과를 바탕으로 파일럿 테스트를 실시한 결과, 수평스티프너로 보강된 RBS 접합부 (SR)와 연장된 수평스티프너를 가진 접합부(LH)는 우수한 변형능력을 보였다.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.253-261
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• 1998

The buckling length of exterior beam-columns of the first floor in moment resisting steel frames with weak beams is uncertain when plastic hinges occur at the ends of weak beams due to seismic loads. The objective of this study is to investigate the buckling strength of concrete-filled tubular beam-columns and to suggest the reduced buckling length of them to apply to the beam-column design code. The exterior beam-columns are modelized with horizontal displacement restraint springs. Their strength and reduced buckling length are evaluated by numerical analysis.