• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.253-256
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• 2008

Although researches on the beams strengthened with Fiber reinforced Polymers (FRPs) have recently been conducted around the world, there are few researches on the beams with FRPs under a sustained load. This paper presents the behavior of the beams with Carbon Fiber Reinforced Polymers (CFRP) and Glass Fiber Reinforced Polymers (GFRP) under a sustained load during 300 days. Strains of steel and FRP reinforcement were measured in order to investigate the behavior of the beams. Additionally, Adjusted Effective Modulus Method (AEMM) and Ghali and Farve's method were used to predict increase in the stress and strain caused by creep and shrinkage. Through the experiment, it was found that the beam with CFRP is more effective than the beam with GFRP in terms of flexural strengthening. Compared with analytical results, it was indicated that strains of tension steels were overestimated, whereas strains of compression steels were underestimated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.1-9
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• 2014

Recently, natural aggregate was adequate to supply the demand due to increase of building construction. National pollution induced by construction waste caused by the reconstruction and redevelopment was cited as the major social issues in Korea. Therefore, government are required by law to use the recycled aggregate. In order to consider safety, KS F 2573 recommend that recycled aggregate with below design strength 27MPa and replacement ratio of 30%. This study on flexural behaviors of reinforced concrete beam was conducted and the specimens employed in test were planed with high strength concrete (40, 50 and 60MPa) and recycled aggregate replacement ratio (0, 30, 50, 100%). Although the flexural strength of reinforced concrete beam has trendy to decrease with increase of replacement ratio, it is meet to KCI 2007. The comparison results show that reinforced concrete beam using recycled aggregate can apply as flexural member in building construction.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.216-219
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• 2007

본 논문에서는 영상 인식을 위해 그레이 레벨로 획득된 영상을 이진화할 때 발생되어 패턴의 윤곽선을 울퉁불퉁하게 만드는 랜덤 노이즈를 제거하기 위한 방법으로 체인 코드 트리밍(chain code trimming) 을 제안한다. 제안된 방법은 패턴의 외부 윤곽선과 내부 윤곽선의 체인 코드 분석을 통해 랜텀 노이즈의 체인 코드를 제거, 교정함으로서 이루어진다. 실험에서는 트리밍을 사용하기전과, 단순 트리밍을 한 경우, 체인 코드 트리밍을 한 경우를 서로 바로, 분석한다. 실험 결과는 패턴에 첨부되었던 랜덤 노이즈가 모두 성공리에 제거된 것을 보인다.

• Journal of Korean Society of Steel Construction
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• v.19 no.4
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• pp.413-423
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• 2007

Slimfloor composite-beam systems could considerably reduce the story height of a building if the steel beam would be installed deep into the concrete floor slab. However, as the depth of the steel beam's installation is limited, it cannot cope with the various demands of building systems. To address this problem, a profiled steel beam section that can control the depth of the steel beam's and slabs' installation was developed in this study. Presented herein are the results of an experiment that was conducted focusing on the flexural behavior of the partially connected composite beams with profiled steel beams encased in composite concrete slabs. Five full-scale specimens with different slab types, with or without shear connection and reinforcement bars, were constructed and tested in this study. As a result, the shear bond stress without an additional shear connection was found to be $0.20{\sim}0.76N/mm^2$due to the inherent mechanical and chemical bond stress.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.83-84
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• 2010

Precast beam column joints with thru-connectors are developed from precedent study. The seismic performance is evaluated by experimental method. The test results of the precedent study showed that failure modes for all specimens were a compression failure by characteristics of unbonded tendon. Thus, variable considered in the research program for a tensile failure include the use of dog-boned longitudinal steel and concrete confined with steel spirals. The analysis of structural characteristics and evaluation of seismic performance of specimens was conducted by the experimental way. Comparison of result with the test specimens indicates that seismic performance is higher than the precedent study due to concrete confinement effect from steel spirals.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.667-674
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• 2015

In this paper, shear behavior of concrete wide beam reinforced with plates with openings was evaluated. For this evaluation, evelen specimens were manufactured. One specimen was non-shear reinforced, five specimens were reinforced with steel plates and the other five specimens were reinforced GFRP plates. Shear strengths measured through experiments were compared with ones calculated from the equation provided by ACI 318. Longitudinal spacing of shear reinforcement, transverse spacing of shear reinforcement and shear reinforcement material were considered as variables. Test results showed that the shear strength increased as the transverse and longitudinal spacing of shear reinforcement became narrow. Also, regardless of material type of shear reinforcement, the shear capacity was similar when the amount of shear reinforcement was the same.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.76-85
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• 2021

In this study, a shear experiment was conducted to evaluate the structural performance of RC members according to the shape of web opening reinforcement. For a total of 4 RC members specimens, the main variables were with or without web openings, with or without web opening reinforcement, and shape of web opening reinforcement, respectively. In this study, a spiral web opening reinforcement with a mixture of square and octagonal shapes was proposed and compared with the existing band type. As a result of the experiment, the specimen with the proposed web opening reinforcement showed that the shear capacity and the energy dissipation capacity increased compared to other specimens. It was confirmed that the web opening reinforcement proposed in this study had a positive effect on the shear performance and crack control of RC members with web openings.

• Journal of Korean Society of Steel Construction
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• v.29 no.6
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• pp.479-486
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• 2017

Steel beams with corrugated web have been widely used in the steel structures. However, it is challenging to weld the section between the corrugated web and the flange straight, which increases the cost of production. In order to solve this issue, steel beam with intaglio and embossed web (It is called an IEB) was invented. A web with embossment is produced by cold pressing and welded to flange by automatic welding machine. The loading tests were conducted to investigate the load-carrying capacity of IEB, and its test result was compared with that of H-shaped beam having a same size of flange and web. The test results of IEB series showed about 40% higher load capacities than H-shaped series. As a result of comparing the IEB specimen with Eurocodes for steel beams with corrugated web, all of specimens tested in this study did not meet the design value. Therefore, it is difficult to apply existing formula to IEB and new design formula should be presented for field application.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.31-39
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• 2012

Recently new construction and reconstruction of the bridge have been required to minimize traffic congestion, environmental disadvantage, to reduce the period of construction, and to improve the quality and workability during the construction. For this reason, the application of modular bridge system, which is assembly of the structural members, is necessary to prepare for near future. Fall of girders can occur at the moment to connect between precast girders during the construction, so appropriate cross beams should be installed to solve the mentioned problem. In this study, understanding the structural characteristics and domestic and international case of cross beam, alternative cross beam system for modular bridge was developed. To inspect the structural characteristics of the alternative system, specimens were built and static loading test was performed. Afterward, the behavior of cross beam interms of joints and load distribution was observed. Experimental results were analyzed and compared with each data. Therefore, the appropriate cross beam system for modular bridge will be chosen and proposed in this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.41-44
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• 2008

Fiber Reinforced Polymers (FRPs) have recently been highly used for repairing and strengthening civil structures due to their superior material properties. By using FRPs, external bond method is the most used method in the construction industry. Although many researches on reinforced concrete externally strengthened with FRPs have been conducted, time-dependant behaviors of the beams have not been investigated yet. This paper documents a series of beam experiments that were carried out to evaluate time-dependant behavior. Three RC beams were built and the parameters considered in this experiment were types of FRPs. Through these experiments, it was proved that the beam strengthened with CFRP was more effective than that with GFRP in terms of time-dependant behavior.