• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.552-560
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• 2004

Stone column is a soil improvement method and can be applicable for loose sand or weak cohesive soil. Since the lack of sand in Korea, stone column seems one of the most adaptable approach for poor ground as a soil improvement method. However, this method was not studied for practical application. In this paper, the most effective design parameters for the being capacity of stone column were studied. The parametric study of major design factors for single stone column was carried out under the bulging and general shear failure condition, respectively. Especially, a test result of single stone column by static load was compared with the bearing capacity values of suggested formulas. The analysis result showed that the ultimate bearing capacity by the formula was much less than the measured value by the static load test. Especially, the result of the parametric study under general shear failure condition showed that the bearing capacity has apparent difference between each suggested formulas with the variation of the major design parameters. Therefore, the result of this study can be a suggestion which is applicable for the field test and the future research.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1132-1143
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• 2008

A single Column/Shaft which extended the pile to the column of the bridge with same diameter has better safety and economical profit, but it usually has larger lateral displacement due to lateral loads such as wind, earthquake, wave, etc. A series of horizontal pile load testing were performed to study the lateral behavior of single column/shaft with varying different free lengths and embedded pile lengths. Eight instrumented test piles were cast-in-placed by bonding strain gauges at certain locations on both faces of the pile to measure bending moment, from two-way loadings. Linear variable differential transformers(LVDTs) were installed to measure the lateral pile displacement. Based on this, it is found that the test single column/shaft with different free lengths shows different failure modes. If the test pile has a longer free length, the failure occurs at the near the ground surface, but the shorter one's failure occurs at the below the ground surface.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.229-245
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• 2017

Post-earthquake observations revealed that seismic performance of beam-column connections in precast concrete structures affect the overall response extensively. Seismic design of precast reinforced concrete structures requires improved beam-column connections to transfer reversed load effects between structural elements. In Turkey, hybrid beam-column connections with welded components have been applied extensively in precast concrete industry for decades. Beam bottom longitudinal rebars are welded to beam end plates while top longitudinal rebars are placed to designated gaps in joint panels before casting of topping concrete in this type of connections. The paper presents the major findings of an experimental test programme including one monolithic and five precast hybrid half scale specimens representing interior beam-column connections of a moment frame of high ductility level. The required welding area between beam bottom longitudinal rebars and beam-end plates were calculated based on welding coefficients considered as a test parameter. It is observed that the maximum strain developed in the beam bottom flexural reinforcement plays an important role in the overall behavior of the connections. Two additional specimens which include unbonded lengths on the longitudinal rebars to reduce that strain demands were also tested. Strength, stiffness and energy dissipation characteristics of test specimens were investigated with respect to test variables. Seismic performances of test specimens were evaluated by obtaining damage indices.

• 한국자동차공학회논문집
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• 제8권6호
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• pp.130-141
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• 2000

The virbration characteristics of a passenger car steering column are studied by using a modal test and a finite element (FE) analysis. To verify the FE model and the results, an experiment using the impact exciting method is performed. Two types of the steering column in this study are considered as follows; (ⅰ) the non-tilt type steering column and (ⅱ) the upper-tilt type steering column. The experimental results are compared with those o the FE analysis, and it ti shown that the results agree with each other. The effects of various design parameters such as the bracket thickness, the column diameter on the natural frequencies are also investigated by FE analysis.

• 콘크리트학회논문집
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• 제26권4호
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• pp.545-553
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• 2014

이 연구는 PC 보-기둥 접합부의 일반적인 거동의 접합 상세에 따른 통합적 평가 방안을 제안하였다. 이 연구는 접합부의 파괴 패턴과 이에 연관된 접합부 상세의 특징을 정량적으로 표현하기 위해 접합부와 각 요소들이 보유한 변형기여분을 사용할 것을 제안하였다. 이에 따라 PC 접합부는 '일체식 접합부'와 '연결식 접합부'로 크게 분류되었다. 접합부의 분류를 위한 기준 사항의 제안 및 검증을 위해 네 개의 보-기둥 실험체의 실험을 수행하였다. 실험은 일반적인 보-기둥 접합부의 실험 방법과 같은 방법으로 진행되었다. 가력은 접합부 상부 기둥의 끝단에서 수행되었으며, 보 양단은 힌지로 고정되었다. 변형기여분의 평가를 위해 총 34개의 LVDT가 주요 변형이 발생할 것으로 예상되는 곳에 설치되었다. 실험 결과 세 개의 실험체에서 나타난 각 요소들의 변형기여분은 수치적으로 다른 특성을 가지고 있는 것을 확인할 수 있었다. 실험 결과를 기반으로 접합부의 변형 정도와 다른 요소들의 변형 정도에 의거하여, 접합부의 변형이 적고 보의 휨 변형이 크게 나타나는 강한 접합부와 접합부의 변형이 용인되는 연성 접합부로 일체식 접합부를 분류할 수 있었다.

• 한국지반환경공학회 논문집
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• 제18권2호
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• pp.59-65
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• 2017

해양 매립 공사는 해저의 해성점토를 해수와 함께 준설하여 매립지로 이동시켜 매립지를 형성시키는 공사이다. 매립지가 형성되는 과정에서 준설토는 침강-퇴적-압밀 과정이 진행되며 이 과정에서 압밀과정은 소요되는 시간과 침하량이 크기 때문에 매립지를 계획하는 해양 매립 공사에서 매우 중요한 결정인자로 사용하게 된다. 준설토의 침하량과 소요되는 시간을 예측하기 위한 방법으로 국내에선 Yano가 제안한 Column 실험이 보편적으로 사용되고 있다. 그러나 Yano의 Column 실험은 준설토의 침강압밀특성을 확인하기 위해 장시간이 필요한 단점이 있다. 따라서 본 연구에서는 장시간이 소요되는 Column 실험의 단점을 보완해 단시간에 준설토의 침강압밀특성을 확인하기 위한 방법으로 원심모형실험을 활용하였다. 그 결과 효율적으로 준설토의 침강압밀특성을 확인하기 위해 원심모형실험을 활용할 수 있는 것으로 사료된다.

• 한국강구조학회 논문집
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• 제29권6호
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• pp.411-422
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• 2017

본 연구에서는 콘크리트피복 원형충전강관 기둥을 적용한 합성구조 접합부의 거동특성과 내진성능을 평가하기 위하여, 기둥-플랜지 접합부에 대한 인장실험과 보-기둥 접합부에 대한 반복하중 실험을 수행하였다. 기둥-플랜지 인장실험은 피복콘크리트의 유무와 플랜지 폭, 인장철근 보강을 변수로 하여 5개의 실험체에 대하여 하중재하능력과 파괴모드를 분석하였다. 실험결과, 접합부에서의 플랜지 단부 폭을 200mm에서 350mm로 증가시킬 경우 연결부의 강도 및 강성이 각각 1.61배와 1.56배가 증가했고, 인장철근을 보강할 경우 추가적으로 강성과 강도가 각각 1.35배와 1.92배 증가했다. 접합부 반복하중 실험에서는 접합 상세를 변수로 3개의 외부접합부 실험체를 구성했다. 접합부 보강상세로는 인장철근 보강과 강관의 두께, 수직강판 보강을 고려하였다. 모든 접합부 실험체는 보에서 뚜렷한 휨항복이 발생하였으며 접합부의 손상은 제한적이었다. 특히, 강재보가 강관에 직접 용접되는 경우 보의 웨브를 통해서도 하중이 전달되기 때문에, 플랜지 인장실험 결과보다 보수적인 설계가 가능하며, 접합부 강관 두께를 증가시키거나 수직강판으로 보강한 경우에는 추가적으로 패널존의 전단내력이 증가하는 것으로 나타났다.

• 한국공간구조학회논문집
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• 제22권3호
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• pp.73-80
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• 2022

Unlike the CFT retrofit method, The EPFT retrofit method, which fills the steel tube with engineering plastic, does not require a separate concrete forming work and is a lightweight seismic Retrofit Method. In this study, an prototype model of the EPFT was proposed, and to analyze the seismic performance, an independent specimens and a reinforced concrete column were fabricated to conduct a seismic performance test. As a result of loading test of the independent specimens, the strength was increased compared to the steel tube column without internal filling, and the ductility ratio did not significantly increase due to the falling off of the weld. As a result of loading test of the concrete reinforcement specimen, the strength, ductility ratio, and energy dissipation were increased, and the number of cracks by loading step decreased compared to the non-reinforced specimen.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.405-410
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• 2001

To investigate factors influencing the effective width of. SRC column-steel beam joint resisting the moment as strut, six specimens are designed and tested. Parameters in the test are column width, beam height and horizontal tie within beam depth. From the test, using either wide column width or ties, strength and stiffness of joint were developed. The lower beam height the specimens showed the lower moment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.146-149
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• 2006

In many previous studies, a prestressed concrete column has a larger flexural strength, shear strength and restoring force than a RC column. Recently, a precast prestressed concrete column is rising up a very rational column structure in that a economic aspect. In a precast prestressed concrete column, it makes in a factory. So, it needs a small construction site and acquires a higher durability than a cast in place concrete column. Seven precast concrete columns were tested under a constant axial load and a cyclically reversed horizontal load to investigate the performance. It is designed with a hollow section and consisted of 4 segments. The main variables of the test were a amount of prestressed, a type of joints and a boding type of strands. The test results show that the performance of a precast prestressed concrete column; failure mode, maximum load, energy dissipation and stiffness degradation.