• Steel and Composite Structures
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• 제5권5호
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• pp.375-394
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• 2005

An experimental study was conducted to develop a new base plate anchorage system for concrete filled tubular column under an axial load and a moment. The column was connected to a concrete foundation using ordinary deformed reinforcing bars that are installed at the inside and outside of the column. In order to investigate the moment resisting capacity of the system, horizontal cyclic loads are applied until the ultimate condition is reached with the axial load held constant. To derive a design method for moment resisting capacity, the reinforced concrete section approach was investigated with the assumption of strain compatibility. The results by this approach agreeded well with those of experiments when the bearing pressure of confined concrete and tangent modulus of steel bars are assumed appropriately. Also, it was found that the column interaction curve can be used to predict the yield strength of the base plate system.

• 콘크리트학회지
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• 제10권6호
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• pp.213-222
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• 1998

투수성 폴리머 콘크리트의 공극에 오염물질의 침투로 내구성 및 투수성능이 저하될 수있어 각종 필터용 폴리머 모르터를 그 위에 타설한 후, 압축강도, 휨강도 및 인장접착강도의 역학적 성질과 경화수축 및 투수성능을 실험을 실시하였다. 실험결과, 투수성 콘크리트의 압축강도의 증가와 함께 투수계수는 낮아졌으며, 충진재-결합재비의 증가에 따라 강도의 증가는 현저하였다. 투수성 폴리머 콘크리트의 압축강도와 투수계수는 9.4 MPa~1.93cm/s범위로서 배합에 따른 영향이 크게 나타났다. 필터용 폴리머 모르터를 타설한 투수성 폴리머 콘크리트의 역학적 성질은 쇄석을 필터로 사용하였을 때 가장 우수하였으며, 투수성 폴리머 콘크리트의 경화수축은 필터와 베이스 콘크리트 사이의 접착력에 영향을 크게 받음을 알 수 있었다. 본 연구결과, 투수성 폴리머 콘크리트의 각 배합조건에 따른 경제성과 성능면에서 균형을 이룰 수 있는 최적배합비를 제안할 수 있었으며 투수성 폴리머 콘크리트의 제작과응용면에 필요한 기초자료를 얻을 수 있었다.

• Earthquakes and Structures
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• 제10권2호
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• pp.293-311
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• 2016

A parametric study on the nonlinear seismic response of isolated reinforced concrete structural frame is presented. Three prototype frames designed according to the 1954 Hellenic seismic code, with number of floor ranging from 1 to 3 were considered. These low rise frames are representative of many existing reinforced concrete buildings in Greece. The efficacy of the implementation of both lead rubber bearings (LRB) and friction pendulum isolators (FPI) base isolation systems were examined. The selection of the isolation devices was made according to the ratio $T_{is}/T_{fb}$, where Tis is the period of the base isolation system and $T_{bf}$ is the period of the fixed-base building. The main purpose of this comprehensive study is to investigate the effect of the isolation system period on the seismic response of inadequately designed low rise buildings. Thus, the implementation of isolation systems which correspond to the ratio $T_{is}/T_{fb}$ that values from 3 to 5 is studied. Nonlinear time history analyses were performed to investigate the response of the isolated structures using a set of three natural seismic ground motions. The evaluation of each retrofitting case was made in terms of storey drift and storey shear force while in view of serviceability it was made in terms of storey acceleration. Finally, the maximum developed displacements and the residual displacements of the isolation systems are presented.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.237-242
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• 1998

Covering mortar as a filter for permeable polymer concrete is necessary for good permeability from filtration continuously. Therefore, this paper is intended as an evaluation of the mechanical properties and permeability of permeable polymer concrete covered with polymer mortar as a filter. An optimum permeable polymer concrete is selected in various mix proportions, and three different polymer mortars were cast immediately following on the casting of the base permeable polymer concrete. And they are tested for compressive and flexural strengths, adhesion in tension, hardening shrinkage and permeability . From the test results, binder and filler contents in mix proportions had a great influence on the permeability of polymer concretes. The mechanical properties of permeable polymer concretes covered with polymer mortars using crushed stone are superior to other filters, and hardening shrinkage is the smallest in filters. It is apparent that adhesion between the base permeable polymer concrete and polymer mortar is affected by the degree of hardening shrinkage. From this study, proper mix proportions can be recommended in the consideration of properties of the permeable polymer concrete.

• 레미콘
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• 7호통권68호
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• pp.9-16
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• 2001

Execution of exposed concrete has some problems such as segregation, surface honey comb and insufficient surface flossing due to unsuitable mix proportion and unfavorable construction in our field. Therefore, in this paper, field application of exposed concrete at training center building of Chongju university in Daecheon are carried out based on the mixing data obtained from laboratory test. Base concrete are made in accordance with mixing data. Segregation reducing type superplasticizer developed are applied in order to flow the vase concrete with out segregation of materials. According to test results, air content shows to be reduced after flowing. Compressive strength of flowing concrete is higher than that of base concrete about 7%. Surface glossing is reducing as the age goes on. It is improved about 10% compared to that of vase concrete.

• 한국도로학회논문집
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• 제13권1호
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• pp.239-249
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• 2011

섬유보강 콘크리트를 이용하여 도로 포장의 기층을 형성하고 그 위에 아스팔트 또는 콘크리트로 표층을 구성함으로써 기능적인 측면과 구조적인 측면 모두에서 우수한 공용성을 발휘할 수 있는 복합포장 공법을 개발하기 위한 기초 연구로써 본 연구에서는 섬유보강 콘크리트 기층이 환경하중을 받을 때의 거동을 수치 해석을 통해 중점적으로 분석하였다. 이를 위해 2차원 유한요소해석 모델을 개발하였으며 이러한 모델을 사용하여 기층 슬래브 두께, 열팽창계수, 탄성계수, 인장 및 압축강도 등의 변수에 대하여 민감도 분석을 수행하였다. 기층의 거동으로는 균열간격과 균열틈 등 균열 특성을 선정하였다. 수치 해석 결과 고려한 변수가 균열간격 및 균열틈에 미치는 일반적인 영향을 파악할 수 있었으며, 기층 거동에 민감한 영향을 미치는 인자를 선정할 수 있었다. 이러한 결과는 표층 재료와 적절히 조합될 수 있는 섬유보강 콘크리트 기층의 재료 특성을 결정하는 기반이 될 것이다.

• Structural Engineering and Mechanics
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• 제10권6호
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• pp.533-543
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• 2000

To prevent major cracking and failure during earthquakes, it is important to design reinforced concrete liquid storage structures, such as water and fuel storage tanks, properly for the hydrodynamic pressure loads caused by seismic excitations. There is a discussion in recent Codes that most of the base shear applied to liquid containment structures is resisted by inplane membrane shear rather than by transverse flexural shear. The purpose of this paper is to underline the importance of the membrane force system in carrying the base shear produced by hydrodynamic pressures in both rectangular and cylindrical tank structures. Only rigid tanks constrained at the base are considered. Analysis is performed for both tall and broad tanks to compare their behavior under seismic excitation. Efforts are made to quantify the percentage of base shear carried by membrane action and the consequent procedures that must be followed for safe design of liquid containing storage structures.

• International Journal of Concrete Structures and Materials
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• 제8권1호
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• pp.1-14
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• 2014

In the present paper, a behavioral model is proposed for study of the individual contributions to shear capacity in shear-critical reinforced concrete members. On the basis of the relationship between shear and bending moment (V = dM/dx) in beams subjected to combined shear and moment loads, the shear resistant mechanism is explicitly decoupled into the base components-beam action and arch action. Then the overall behavior of a beam is explained in terms of the combination of these two base components. The gross compatibility condition between the deformations associated with the two actions is formulated utilizing the truss idealization together with some approximations. From this compatibility condition, the ratio of the shear contribution by the tied arch action is determined. The performance of the model is examined by a comparison with the experimental data in literatures. The results show that the proposed model can explain beam shear behavior in consistent way with clear physical significance.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.599-602
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• 2005

In this research, the characteristics of the strength development and chloride attack resistance on the concrete using high early strength cement by steam curing temperature condition were studied. As a result, It is observed that the early strength(16hr) is increasing and the strength of 28 days is decreasing, according as the rising of the steam curing temperature without the kinds of base cement(OPC and high early strength cement). On the other hand, it is observed that the more the contents of the unit binder(base cement + GGBF) is abundant, the more the steam curing temperature can be reduced in case of the high early strength. Also, the chloride attack resistance is improved according as the amount of GGBF is increased with the kinds of base cement(OPC and high early strength cement).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.38-39
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• 2021

Recently, 67% of defect and tenant lawsuits were identified as leaks due to cracks. In particular, when the final finish of the roof of a building is designed with base concrete, complex deterioration occurs due to the harsh environment such as shrinkage and expansion due to external temperature changes, freezing and thawing, and the use of calcium chloride due to snow accumulation. Therefore, it is intended to secure long-term durability by reducing cracks in the base concrete by using waste fibers, which are industrial by-products.