• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.511-514
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• 2005

Recently, to obtain the reliable data on the state of the structure, various non-destructive techniques are available. The infrared thermography technique is used in detection of cracks, flaws of concrete structures and buildings. In this paper the infrared thermography technique using the difference of surface temperature was studied. Also this paper is case study that the inspection of building's tile using infrared thermal video.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4A
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• pp.603-609
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• 2008

The recycled aggregates which were produced from the waste concretes have the disadvantages of inferior properties for natural aggregate. Therefore, in order to reuse the recycled aggregate it must be solved to improve the quality of recycled aggregate. In this study, the quality of recycled aggregate was improved by the surface treatment method using the colloidal silica solution. And, in order to examine the possibility of reusing the surface coated recycled aggregate in constructing concrete structures, we studied the mechanical properties and durability of the concrete using the surface coated recycled aggregates and the other concrete.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.4
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• pp.403-409
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• 2013

Shear behavior of concrete beams reinforced with steel and/or FRP bar is studied through experimental tests. Experimental parameters includes the mechanical properties of reinforcements in shear and bending, and the ratio of shear reinforcement. The validity of the modified truss analogy, that has been widely accepted as a basis for the practical shear design of concrete beams, has been examined thoroughly by analyzing experimental results. The experimental results indicate that the modified truss analogy cannot be directly adopted to the shear problem of concrete beams reinforced with FRP bar.

• Resources Recycling
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• v.10 no.1
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• pp.7-15
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• 2001

We can reuse the portion of simple reclamation and the construction by-products. Until now, we have discarded concrete by simply throwing away or dumping in underground. Therefore, we attempted to propose the technical directions for the reuse of waste concrete as the recycled concrete aggregates and concrete structural materials. As a testing result, It is reasonable that standards are substitution of recycled aggregates under 30%, maximum steel ratio, under 70% of balanced steel ratio, under shear span ratio 0.2 for deep beam criteria for safety and Zsutty's equation is reasonable for estimation of factored shear strength

• Journal of The Korean Digital Architecture Interior Association
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• v.13 no.4
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• pp.61-68
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• 2013

Concrete structure is not the only material vulnerable to physical and chemical processes of deterioration associates with severe conditions. Deterioration of the concrete structure, however, occurs more progressively from the outside of the concrete exposed to severe conditions. Especially, Carbonation, chloride ion attack is more important factor of concrete durability. This study is interested in manufacturing the self-cleaning concrete surface impregnant including TEOS, lithium silicate for the repair of the exposed concrete surface and the color concrete requiring the advanced function in view of the concrete appearance. Form the results, TEOS and lithium silicate are very effective that increasing the concrete durability using self-cleaning concrete impregnant. Self-cleaning concrete impregnant specimens is satisfied with performance requirement of KS standard in adhesion test in tension but the reinforcement of concrete substrate is slight. So, the self-cleaning concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

• Computational Structural Engineering
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• v.9 no.1
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• pp.65-76
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• 1996

The initiation and growth of microcracks or microvoids inside concrete results in the progressive degradation of concrete. This damage processing along processing along with plastic deformation is main cause of nonlinear behavior of concrete. In this study, a continuum damage model of concrete is developed for the analysis of the nonlinear behavior of concrete due to damage and elasto-plastic deformation. Anisotropic damage tensor is used to describe the anisotropy of concrete and hypothesis of equivalent elastic energy is used to define the effective elastic tensor. The damage model including the damage evolution law and constitutive equation is derived with damage variable and damage surface which is defined by damage energy release rate by using the Helmholtz free energy and dissipation potential based on the thermodynamic principles. By adopting a typical plasticity model of concrete, plasticity of concrete is included to this model. Afinite element analysis program implemented with this model was developed and finite element analysis was performed for the analyses of concrete subjected to uniaxial and biaxial loadings. Comparison of the results of analysis with those of experiments and other models shows that the model successfully predicts the nonlinear behavior of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.297-298
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• 2009

In this paper, it was to investigate different types of mortar properties using a chloride attack protection agent by evaluating mixing ratio of this particular agent, including 3% increments. The results showed that the compressive strength and chloride ion penetration resistance of mortar by using chloride attack protection agent were improved than non-added mortar.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.10-13
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• 2010

세그먼트 자중 등에 의한 휨모멘트와 케이블 수직압축력에 의한 합성응력이 발생되고 바닥판 경간비가 변하는 사장교의 시공단계에서는 전단지연의 영향범위가 다를 수 있다. 이 연구에서는 1면 케이블 콘크리트 박스 사장교를 대상으로 시공단계시 보강형에 고려되어야 할 합성응력에 의한 유효플랜지폭을 분석하였다. 그 결과 바닥판 경간비가 0.38 이하의 범위에서 보강형의 전폭을 유효플랜지폭으로 적용할 수 있는 것으로 해석되었다. 따라서 시공단계시 변화되는 바닥판 경간비의 크기에 관계없이 전폭을 유효플랜지폭으로 반영하는 실무관행은 안전측 설계가 되지 못할 수 가 있다. 바닥판 경간비가 작아짐에 따라서는 전폭과 캔틸레버 구조계로 유효플랜지폭을 결정하는 것이 타당하다. 이 연구에서는 수직력에 대한 도로교설계기준의 유효플랜지폭 규정에 대한 평가도 수행하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.9-19
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• 1981

Using superplasticizer or the methods of autoclave curing is the most typical and practical of the ways to make high strength concrete. In this study the high strength concrete piles by way of centrifugal forming and hand compacting, are put to the freezing and thawing test after the process of autoclave curing, water curing after steam curing, or stand water curing. And the relation of such piles to durability, the rate of strength decrease, and the rate of weight variation is shown. The durability of those test piles throughout freezing and thawing test proves to be comparatively sufficient in the above-mentioned curings when the piles contain a proper quantity of air. But it is also acknowledged that without A.E agent, the high strength concrete piles of autoclave curing is higher than those of the other curing in strength, but lower in modulus of dynamic elasticity and their durability factor after the test is much lower.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.549-552
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• 2009

본 논문에서는 재료적 성능이 우수하며 경량재료로서 최근 건설구조물에 활용하고자 하는 연구가 활발히 진행되고 있는 섬유보강재료(FRP : Fiber Reinforced Polymer)를 이용한 합성구조인 CFFT(Concrete Filled FRP Tube)의 설계프로그램을 개발하여 제안하고자 하였다. 먼저, CFFT구조는 FRP관에 의해 철근콘크리트가 구속되는 구조로서 기둥과 같이 축력이 도입되는 경우 포아송효과에 의한 변형을 FRP관이 구속효과를 줌으로써 콘크리트의 역학적 거동을 개선하게 되는데 본 연구에서는 실험에 의해 검증된 식을 제시하였으며 이를 바탕으로 CFFT구조를 설계하는 알고리즘을 제안하였다. 또한 CFFT구조는 FRP관의 구속으로 인해 고강도콘크리트와 긴장재의 도입이 가능한 구조로서 이에 대한 설계도 포함하였다. 그러나 이방성재료인 FRP의 설계와 동시에 FRP관에 의한 구속효과를 고려하는 CFFT구조의 설계는 일반 실무설계자들에게는 다소 난해한 작업으로써 전산화 설계프로그램의 필요성이 대두되어 본 연구에서 CFFT구조의 설계프로그램을 개발하였다. 개발된 설계프로그램의 검증을 위해 일반 철근콘크리트기둥, CFFT기둥, 고강도콘크리트와 PS긴장재를 도입한 CFFT기둥을 설계한 결과, 매우 실용적이며 타당한 설계가 수행될 수 있음을 확인하였다.