• 한국건축시공학회지
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• 제3권1호
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• pp.85-91
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• 2003

This study aims to provide basic data that can be applied to construct real structures. For this, an experimental structure was manufactured to identify durability according to age of fiber-reinforced concrete which contains fiber reinforcement materials (polypropylene fiber, steel fiber, cellulose fiber) and structural property about flexural behavior and destruction of reinforced concrete beam, and a relation between load and deflection, crack and destruction according to increase of load and ductility capacity was examined. Fiber-reinforced concrete materials and other constructional materials were experimented and the result is presented as follows: The results obtained through material test of concrete and static experiment of members usings 1. The experiment shows that compressive strength of fiber-reinforced concrete was lower than that of non-reinforced concrete. 2. As a result of strength experiment according to different kinds of fiber, compressive strength of an experimented structure that contains cellulose fiber was the highest when age was 28. 3. When deflection of reinforced concrete beam was examined, it was reported that ductility capacity of the experimented structure that contains fiber-reinforced concrete was raise than that of non-reinforced concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.307-308
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• 2021

Corrosion of reinforced steel inside concrete is an important cause of performance degradation of reinforced concrete structures and has a profound influence on the durability of structures. In this study, three groups of different reinforced concrete structures exposed to the natural environment were subjected to chloride ion accelerated corrosion tests for up to 180 days. The corrosion velocity and ambient temperature of the samples were measured and recorded every day. Based on Faraday's law, the corrosion speed of steel bars could be measured, and the ambient temperature and humidity around the structure in corresponding time were compared. Through the measurement of up to 180 days, the influence of external ambient temperature and humidity on the corrosion speed of steel bars inside the concrete structure was found out. The results show that there is a good direct proportional relationship between temperature and corrosion speed. When the ambient temperature increases by 15℃, the corrosion rate increases by about one time.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.518-521
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• 2006

The purpose of this study is to evaluate structural performance of concrete beam reinforced simultaneously with GFRP and steel rebar. Because the GFRP has lower elastic modulus than steel or CFRP, serviceability for concrete structure can be an issue. According to the test result, the hybrid reinforced specimen showed better stiffness improvement than the specimen reinforced with only GFRP rebar. From an additional research on design parameter and reliability analysis, the field adaptability can be proved.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.491-496
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• 2001

In recent years, the research and development about the new material proceed rapidly and actively in the building industry. As building structures become bigger, higher and more specialized, so does the demand for material with higher strength. In the future, we will need to research repair and rehabilitation to make high strength concrete mixed steel fibrous building safe. The carbon fiber reinforced plastic bonding method is widely used in reinforcing the existing concrete structure among the various methods. The repair of initiate loaded reinforced high-strength concrete beams mixed steel fibrous with epoxy bonded Carbon Fiber Sheets(CFS) was investigated experimentally. The CFS thickness and length were varied to assess the peel failure at the curtailment of CFS, The behaviour of the repaired beams was represented by load-longitudinal steel strain relation and failure modes were discussed. The test results indicate that CFS is very effective for strengthening the demand beams and controlling deflections of reinforced high strength concrete beams mixed steel fibrous happen diagonal crack, the increase in the number of CFS layers over two layers didn't effect the increase in the strength of beams.

• 한국전산구조공학회논문집
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• 제34권2호
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• pp.85-91
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• 2021

본 연구에서는 섬유보강콘크리트(SFRC) 구조물의 수치해석을 위한 K&C모델의 보정기법을 소개하였다. SFRC 1축 및 3축 압축강도 실험결과를 기반으로 보정을 수행하였으며, 단일요소 해석결과를 실험결과와 비교함으로써 보정 기법의 검증을 수행하였다. 또한, 변형률 속도의 영향을 반형하기 위해 동적증가계수(DIF)를 고려하여 SFRC 구조물의 발사체 관통해석을 수행함으로써 보정기법의 적용 가능성을 확인하였다.

• 한국건축시공학회지
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• 제8권5호
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• pp.35-42
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• 2008

In this study, a sample was fabricated according to the recycled aggregate replacement level(0%, 30%, 60%), and the steel fiber mixing status in order to use recycled aggregate as a concrete alternative coarse aggregate, and then the materials and structural characteristics of recycled aggregate and steel fiber which impacted the reinforced concrete were analyzed. A conclusion was derived as follows. After considering the results of various material experiments and mock-up test, when a flexural strength and a ductility factor is increased and the replacement level is increased through mixing the steel fiber with the recycled aggregate concrete, the ductility and flexural strength reduction seems to be inhibited by adding the steel fiber. Also, it is indicated that the recycled aggregate has almost-similar compressive strength, tensile strength flexural strength and ductility capacity to the concrete which using the general gone even though the steel fiber is used and the replacement level is increased to 30%. Accordingly, the reinforced concrete frame using the steel fiber mixture and recycled aggregate seems to apply to the actual structure.

• Steel and Composite Structures
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• 제28권1호
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• pp.73-82
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• 2018

This paper experimentally and analytically elucidates the shear behavior and shear bearing capacity of partially prefabricated steel reinforced concrete (PPSRC) columns and hollow partially prefabricated steel reinforced concrete (HPSRC) columns. Seven specimens including five PPSRC column specimens and two HPSRC column specimens were tested under static monotonic loading. In the test, the influences of shear span aspect ratio and difference of cast-in-place concrete strength on the shear behavior of PPSRC and HPSRC columns were investigated. Based on the test results, the failure pattern, the load-displacement behavior and the shear capacity were focused and analyzed. The test results demonstrated that all the column specimens failed in shear failure mode with high bearing capacity and good deformability. Smaller shear span aspect ratio and higher strength of inner concrete resulted in higher shear bearing capacity, with more ductile and better deformability. Furthermore, calculation formula for predicting the ultimate shear capacity of the PPSRC and HPSRC columns were proposed on the basis of the experimental results.

• 한국농공학회지
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• 제30권2호
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• pp.67-81
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• 1988

The purpose of the present study is to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir and to establish a solid foundation for the automatic optimum structural design combined with finite element analysis. The major design variables are the dimensions and steel areas of each member of the structures. The construction cost which is composed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of the working stress design method. The corresponding design guides including the standard specification for concrete structures have been also employed in deraving the constraint conditions. The present nonlinear optimization problem is solved by SUMT method. The reinforced concrete intake-tower is decomposed into three major substructures. The optimization is then conducted for both the whole structure and the substructures. The following conclusions can be drawn from the present study. 1. The basis of automatic optimum design of reinforced concrete cylindrical shell structures which is combined with finite element analysis was established. 2. The efficient optimization algorithms which can execute the automatic optimum desigh of reinforced concrete intake-tower based on the working stress design method were developed. 3. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optImization algorithms developed in this study seem to be efficient and stable. 4. The difference in construction cost between the optimum designs with the substructures and with the entire structure was found to be small and thus the optimum design with the substructures,rnay conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the tensile stress insteel for salb, the minimum lonitudinal steel ratio constraints for tower body and the shearing stress in concrete, tensile stress in steel and maximum eccentricityconstraints for footing, respectively. 6. The computer program develope in the present study can be effectively used even by an unexperienced designer for the optimum design of reinforced concrete intake-tower.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.309-312
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• 2000

Nonuniform temperature distribution due to hydration heat induces thermal stress in mass concrete. At early ages, such thermal stress may induce thermal cracks which can affect on the durability ad safety of the structure. Steel fiber reinforced concrete may be useful when a large amount of energy has to be absorbed, when a high tensile strength and reduced cracking are desirable, of an improvement of thermal conductivity is desirable. In LG IPP Project, the upper part(50cm) of turbine foundation was replaced with steel fiber reinforced concrete to reduce the thermal crack induced by hydration heat. It was shown that the thermal crack control could be successfully achieved by steel fiber reinforced concrete.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.633-636
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• 1998

This study is performed for the purpose of obtaining the fundamental datum to analyse the cause of steel corrosion in concrete and establish the repair strategies of deteriorated reinforced concrete structures due to steel corrosion. To investigate the degree of concrete deterioration, soluble chloride content in harden concrete, the depth of carbonation, cover depth and compressive strength are measured. The progress of corrosion of concrete bridge is electrochemically evaluated. The result shows that in approximately 43% of the structures below -350mV(vs. CSE), the exessive chloride contents is a direct cause of steel corrosion in reinforced concrete structures.