• International Journal of Concrete Structures and Materials
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• 제10권3호
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• pp.307-323
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• 2016

The nonlinear behaviors of recycled aggregate concrete (RAC) frame structure are investigated by numerical simulation method with 3-D finite fiber elements. The dynamic characteristics and the seismic performance of the RAC frame structure are analyzed and validated with the shaking table test results. Specifically, the natural frequency and the typical responses (e.g., storey deformation, capacity curve, etc.) from Model 1 (exclusion of strain rate effect) and Model 2 (inclusion of strain rate effect) are analyzed and compared. It is revealed that Model 2 is more likely to provide a better match between the numerical simulation and the shaking table test as key attributes of seismic behaviors of the frame structure are captured by this model. For the purpose to examine how seismic behaviors of the RAC frame structure vary under different strain rates in a real seismic situation, a numerical simulation is performed by varying the strain rate. The storey displacement response and the base shear for the RAC frame structure under different strain rates are investigated and analyzed. It is implied that the structural behavior of the RAC frame structure is significantly influenced by the strain rate effect. On one hand, the storey displacements vary slightly in the trend of decreasing with the increasing strain rate. On the other hand, the base shear of the RAC frame structure under dynamic loading conditions increases with gradually increasing amplitude of the strain rate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.723-730
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• 2001

Mass concrete of reaction structure was investigated to minimize cracks generated by the heat of hydration. Suggestions are noted in this paper through the experiences of planning, technical study, computational analysis and field instrumentation.

• Smart Structures and Systems
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• 제33권3호
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• pp.189-199
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• 2024

To properly extract the strain components under varying operational conditions is very important in bridge health monitoring. The abnormal sensor readings can be correctly identified and the expected operational performance of the bridge can be better understood if each strain components can be accurately quantified. In this study, strain components under varying load conditions, i.e., temperature variation and live-load variation are evaluated based on field strain measurements collected from a real concrete box-girder bridge. Temperature-induced strain is mainly regarded as the trend variation along with the ambient temperature, thus a smoothing technique based on the wavelet packet decomposition method is proposed to estimate the temperature-induced strain. However, how to effectively extract the vehicle-induced strain is always troublesome because conventional threshold setting-based methods cease to function: if the threshold is set too large, the minor response will be ignored, and if too small, noise will be introduced. Therefore, an autoencoder framework is proposed to evaluate the vehicle-induced strain. After the elimination of temperature and vehicle-induced strain, the left of which, defined as the model error, is used to assess the operational performance of the bridge. As empirical techniques fail to detect the degraded state of the structure, a clustering technique based on Gaussian Mixture Model is employed to identify the damage occurrence and the validity is verified in a simulation study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.142-147
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• 1993

In the reinforced concrete structure, as the height of building structure increases, the accurate estimation of differential column shortening is important factor in the structural design. In this study, the analysis of column shortening is applied to 36-story building structure to be built in time. As a result, it may found that, as the difference of compressive stress become larger, differential shortening effect due to creep and shrinkage are more signicant factor to structural designer.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.721-724
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• 1999

The concrete structure under fatigue load depresses in mechanical capability or breaks down finally because of the fatigue. So recently the study on strengthening methods using bonded plate is widely attended. Which could be constructed under use and without damaging the structure. The intention of this method is to increase the useability of the structure and to recover the strength. So application on fields are sharply increasing. In this study it is tried to develop strengthening methods using notches and anchor bolts which could supply the defect on falling off of the plate at the end.

• 한국안전학회지
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• 제14권3호
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• pp.146-154
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• 1999

The feasibility of using AE for monitoring mechanical failure in concrete structures has been tested. Specifically, the relationship between the fracture and the characteristics of AE signal is theoretically and experimentally investigated. The experimental results manifest that the high sensitivity of AE signal to the fracture of concrete structure makes it a good choice as sensor for monitoring concrete structure.

• 한국세라믹학회지
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• 제47권4호
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• pp.276-282
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• 2010

There are the impregnating layer formation by surface protective materials or impregnants and the adhesion method by polymer, FRP sheet or steel plate in the surface protective method of concrete structure. The surface impregnation method by impregnants improves the durability of concrete structure by modifying the structure of the concrete surface and also have a merit that can be shortly applied in place without the decrease of concrete surface appearance and is easily applied again. This study is interested in manufacturing the concrete surface impregnants including lithium and potassium silicate for the repair of the exposed concrete and the color concrete requiring the advanced function in view of the concrete appearance. The durability and porosity properties was tested for the review of application. The result of this study show that the effective content of silicate ranges 5 to 20% and the separate application of the first impregnant and the second impregnant is effective for the optimum performance. The adhesion in tension is slightly increased but the reinforcement of concrete substrate is slight. So, the concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement.

• 콘크리트학회논문집
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• 제23권5호
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• pp.541-550
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• 2011

많은 연구에서 플라이애쉬 및 바텀애쉬를 사용한 콘크리트에 대한 연구가 진행되고 있지만, 매립회를 사용한 콘크리트 및 실제 크기의 구조물에 대한 성능 평가 연구는 매우 제한적이다. 이 연구는 매립회를 잔골재와 치환하여 실제 크기의 구조물을 제작하고 이에 대한 성능을 평가하는 것을 주안점으로 한다. 1단계 연구 결과에서, 중간 정도의 성능을 가지는 두 가지 종류의 매립회(태안, 삼천포)를 선정하고 두가지 치환율(25%, 50%)을 고려하여 총 5개의 기둥, 슬래브, 벽체를 가진 콘크리트 구조물을 시공하였다. 경화전의 매립회 콘크리트 특성에서 공기량, 슬럼프, 응결 시간이 측정되었으며, 경화된 구조체에서 코어를 채취하여 강도, 염화물 저항성 및 탄산화 실험을 수행하였다. 코어에서 평가된 강도 및 내구 특성은 동일 배합의 공시체 시편에 대한 실험 결과와 비교하였다. 한편 구조물을 대상으로 반발경도, 건조수축, 수화열 특성이 평가되었으며, 기준 콘크리트와의 비교를 수행하였다. 실험 결과 매립회 콘크리트는 기준 콘크리트에 비해 적절한 강도 특성, 내구 특성을 가지고 있었으며, 구조물로 충분히 적용할 수 있음이 검증되었다. 국내 매립지에 따라 플라이애쉬, 바텀애쉬, 미탄소 탄소 등의 함량 제어를 통한 매립회 잔골재의 품질 제어가 수행된다면, 이에 대한 활용이 더욱 증가될 것이다.

• 한국안전학회지
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• 제28권6호
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• pp.29-35
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• 2013

The purpose of this study is to investigate the steel bar corrosion and degree of reinforced concrete bridge, and analyze the cause of corrosion occurrence. Therefore they could ensure the durability and stability as to suggest the corrosion prevention of reinforced concrete structure. To study the corrosion state reinforced concrete structure, We investigate the cover of concrete, the compressive strength by schmidt hammer, the neutralization test of site, the compressive strength of core and the measurement of neutralized depth. As the results of test, the corrosion-grade of reinforced concrete structure which the degree of corrosion is 3, 4 degree get to 18% in the used time of 40 years and the time elapsed of 25 years. Therefore the corrosion of steel bar give rise to public discussion. The degree of corrosion is serious, and the neutralization come to the cover of concrete.

• Steel and Composite Structures
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• 제28권5호
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• pp.527-539
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• 2018

The use of reinforced concrete (RC) shear wall with concrete filled steel tube (CFST) columns and steel fiber reinforced concrete (SFRC) shear wall has aroused widespread attention in recent years. A new shear wall, named SFRC shear wall with CFST columns, is proposed in this paper, which makes use of CFST column and SFRC shear wall. Six SFRC shear wall with CFST columns specimens were tested under cyclic loading. The effects of test parameters including steel fiber volume fraction and concrete strength on the failure mode, strength, ductility, rigidity and dissipated energy of shear wall specimens were investigated. The results showed that all tested shear wall specimens exhibited a distinct shear failure mode. Steel fibers could effectively control the crack width and improve the distribution of cracks. The load carrying and energy dissipation capacities of specimens increased with the increase of steel fiber volume fraction and concrete strength, whilst the ductility of specimens increased with the increase of steel fiber volume fraction and the decrease of concrete strength.