• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.63-71
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• 2005

There were already several studies conducted on the steel-concrete (SC) composite column, which was developedcomplement the weaknesses and maintain the advantages of previous composite columns. The axial compressive capacity of the SC composite column was estimated by the tests in previous studies, but the experiments for the large-scale column could not be performed because of the limitation with the laboratory's capacity. In this study, the analytical study was performed using the general finite element analysis program to reflect the interaction of concrete and steel and the local buckling of steel flange composed of the non-compact section. The appropriateness of the analytical model was verified by the comparison between experimental and analytical results. The nonlinear behavior of full-scale SC composite column was analyzed using the verified analytical model. From these analytical studies, it was concluded that the width-to-thickness ratio of the steel cross-section of the SC composite column should not exceed 25:0. The section area of the link is best when it is over 0.025 dt, and the link distance is to be less than D/2 or 300mm.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.3
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• pp.48-56
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• 2021

Due to the recent earthquake that has occurred worldwide, interest in seismic reinforcement of structures is increasing. In order to improve the seismic performance of the structure, the seismic reinforcement of the column should be made. Various seismic retrofit methods are being developed to improve the seismic performance of columns. In this study, in order to improve the seismic performance of RC columns, an numerical study was conducted to evaluate the seismic performance of the columns by applying a surface constrained pressure. For the numerical study, the experimental study on the column was used, and the failure shape and behavior characteristics of the experimental results and the numerical results were compared. As a result of the numerical study, the ductile behavior of the RC columns occurred according to the strength of the surface constraining stress. In addition, ductile behavior occurred almost constant above a certain surface constrained pressure. Compared with the numerical results and the experimental results, he reinforcing effect of the used seismic reinforcement of the column in experimental study was compared with the value of the surface constrained pressure for the RC column, and the seismic reinforcing effect was examined as the surface constrained pressure value for the RC column. In conclusion, in this work, surface constrained stress and constrained strength for ductile behavior of RC columns are derived. Based on the results derived, it is believed that it can be used as basic data on the review of seismic design methods and seismic performance complementary effects using ductile behavior induction of RC columns.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.400-403
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• 2010

Mega-frame 시스템은 구조적으로 횡력에 가장 효율적으로 저항할 수 있는 구조시스템으로서 200층 이상의 극초고층 건물에 적용되고 있다. 소수의 대형 기둥에 의하여 지지되므로, 기둥의 파괴로 인한 연쇄붕괴의 가능성이 매우 높다. 본 논문에서는 비선형 정적해석을 통하여 다양한 Mega-frame 구조물의 연쇄붕괴 저항능력을 평가해 보았다. 그 결과, Mega-frame 구조물의 연쇄붕괴 거동을 이해하고 이에 합당한 연쇄붕괴 보강방안을 찾으려 한다.

• Journal of the Korean Geotechnical Society
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• v.30 no.11
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• pp.25-37
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• 2014

Clay or sand does not exist alone but various sizes of soil are mixed in the field. In this study, the effect of water content on large deformation of such mixed soils is studied by using soil column tests and a particle method. A soil column with 7 cm in diameter and 13 cm in height, which was made out of kaolinite with sand content of 0, 10, 25, or 50%, was tested for large deformation. Its deformation was monitored with time. While increasing its water content from 40, 60, to 80%, a total of 12 types of soil column tests were carried out. The particle method simulated their deformation with time. A maximum plastic shear modulus, which was a function of undrained shear strength and plasticity index for soils with different water contents, was associated with soil viscosity to simulate large deformation of soil column. When a sand content of soil column was constant, the deformation of soil column increased with increasing water content. When a water content of soil column was constant, large deformation occurred with increasing the sand content. The maximum deformation, which was 22 cm in diameter, was observed in the case of water content of 80% and sand content of 50%. The particle method was able to relatively well simulate such large deformation and stress change of soils.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.221-229
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• 2008

An improved unbonded-type column strengthening procedure using wire rope and T-shaped steel plate units was proposed. Eight strengthened columns and an unstrengthened control column were tested under concentric axial load. The main variables considered were the volume ratio of wire rope and the flange width and configuration of T-shaped steel plates. Axial load capacity and ductility ratio of columns tested were compared with predictions obtained from the equation specified in ACI 318-05 and those of conventionally tied columns tested by Chung et al., respectively. In addition, a mathematical model was proposed to evaluate the complete stress-strain relationship of concrete confined by the wire rope and T-plate units. Test results showed that the axial load capacity and ductility of columns increased with the increase of the volume ratio of wire rope and the flange width of T-plates. In particular, at the same lateral reinforcement index, a much higher ductility ratio was observed in the strengthened columns having the volume ratio of wire rope above 0.0039 than in the tied columns. A mathematical model for the stress-strain relationship of confined concrete using the proposed strengthening procedure is developed. The predicted stress-strain curves were in good agreement with test results.

• KOMUNHWA
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• no.61
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• pp.3-44
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• 2003

The plane structure of dwelling in korean peninsula has been transformed orderly as for shapes of round, square and rectangular in general. The exit and entrance structure take styles of stairs and when they are jotted out, take the slant stairs from the

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.2
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• pp.73-82
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• 2001

본 연구는 실험적 방법과 해석적 방법을 통하여 반복하중을 받는 ├형 철근콘크리트 접합부의 전단특성을 파악함을 목적으로 한다. ├형 접합부는 고강도 재료의 사용으로 인한 체적의 감소 뿐만 아니라, 지진발생 시 반복하중의 작용으로 인한 변동축력 등으로 , 구조적으로 취약한 부분이 될 가능성이 있다. 따라서 본 연구에서는 ├형 접합부의 전단특성을 파악하기 위하여 기동축력, 콘크리트 압축강도, 접합부 전단보강근비를 변수로 한 12개의 실험체를 제작하여 가력실험을 수행하였다. 또한, 유한요소 해석을 수행하여 본 실험결과와의 비교 검토를 통하여 타당성을 검토한 후, 기둥축력과 콘크리트 압축강도의 변화에 대한 변수해석을 통하여 접합부의 전단강도에 미치는 변수는 영향을 파악하였으며, 실험에 의한 실험체의 전단내력을 기존에 제안된 AIJ, ACI 규준 등과 비교 검토하였다. 본 연구의 결로부터 기둥축력과 콘크리트 압축강도가 ├형 철근콘크리트 접합부의 전단강도에 미치는 영향을 확인하였다.

• Journal of Korean Society of Steel Construction
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• v.29 no.2
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• pp.169-180
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• 2017

Cyclic loading tests for beam-to-column weak-axis connections were performed to investigate the seismic performance. In this study, the connections were developed to improve the constructability on the basis of investigation for existing small-size steel structures. The primary test parameter is the number of high-tension bolts which are used to connect steel beam and column using exterior and interior flange plates. Test results showed that the number of bolts had a significant effect on the cyclic behavior of beam-column weak-axis connections. From the analysis of test results, it is concluded that more than four bolts in the connections can satisfy the requirements of semi-rigid connection presented in current design codes. All of specimens showed the bearing failure around bolt holes and fracture at the beam flange. However, when the web height and the flange width is relatively small, the number of the bolts used in the connections might be limited. Thus, the additional research in this area is needed.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.90-90
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• 2011

최근 전 세계적으로 지진의 발생 빈도가 증가하며 그 규모도 점차 커지는 경향을 보이고 있다. 대형지진의 발생 시 저층 구조물의 붕괴로 인한 인명 및 사회, 경제적 피해가 두드러짐에 따라 기존 저층 구조물의 내진보강기법에 관한 연구가 활발히 진행 중인 추세이다. 우리나라의 경우 강도증가형 내진보강공법이 주를 이루고 있어 다양한 내진보강기법의 개발 및 적용이 필요한 실정이다. 따라서 본 연구에서는 지진입력하중 저감형 내진보강기법으로서 강재댐퍼시스템을 제안하여 구조적 성능을 파악하고, 이를 적용한 보강 실험체와 비보강 실험체를 제작하여 정적가력실험을 통하여 그 성능을 비교하였다. 제안된 강재댐퍼시스템은 입력에너지를 소산시키는 내부의 슬릿형 댐퍼와 이를 지지하는 기둥 및 외부 프레임으로 구성되며, 내부 댐퍼는 먼저 항복하여 에너지를 소산시키기 위하여 지지기둥 및 프레임에 사용된 강재보다 강성 및 강도가 적게 계획되었다. 강재댐퍼의 성능실험 결과, 비교적 안정적 거동을 하며, 강성과 강도 및 에너지 흡수능력이 우수하게 나타났다. 보강 및 비보강 실험체의 골조는 기존 학교 건축물의 표준도면을 기준으로 하여 골조의 일부를 대상으로 60% 축소율을 적용하여 계획하였으며, 보강 실험체는 미리 제작된 강재댐퍼시스템을 골조 내에 설치하여 에폭시 주입법으로 부착시공 하였다. 보강 및 비보강 골조 실험체의 정적가력 실험결과 비보강 실험체는 기둥의 휨 항복 후 변형의 증가에 따라 휨 및 전단 균열이 증가하면서 최종적으로 기둥이 전단파괴 되었으며, 보강 실험체는 비보강 실험체에 비하여 기둥 및 보의 균열이 적고, 골조에 골고루 분포되어 파괴 규모가 감소하였다. 최대 강도면에서 보강 실험체는 비보강 실험체에 비하여 약 3.4배 우수하였으며, 초기강성은 약 7배 가량 유리한 것으로 평가되어 제안된 강재댐퍼시스템이 강도면에서 우수한 성능을 나타냄을 알 수 있었다. 또한 두 실험체의 기둥 주근 및 띠철근의 변형률을 비교한 결과, 비보강 실험체는 대부분의 철근이 항복하여 큰 변형을 일으킨 반면, 보강실험체에서는 철근의 항복현상이 나타나지 않았고 댐퍼가 항복을 하면서 큰 변형을 일으켰다. 이를 통해 지진하중 입력 시 댐퍼에서 입력 에너지를 흡수하여 큰 하중을 부담하며, 기존의 구조부재에는 입력 에너지가 낮아 손상이 보다 적게 발생함을 확인하였다.