• 한국구조물진단유지관리공학회 논문집
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• 제6권1호
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• pp.205-212
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• 2002

The deterioration rate of concrete structures in urban area is accelerated due to rapid urbanization and environmental pollution. Repair materials and methods newly introduced in Korea should be investigated whether they are appropriate for the urban environment in Korea. The creek concrete structures are exposed in severe environmental condition than others. Based on these background in mind, the study is focused on evaluation of performance on repair materials used to rehabilitate creek concrete structures. To evaluate the performance of repair materials, four kinds of repair materials were selected based on polymer emulsion. This experimental study was conducted on fundamental performance such as setting time, compressive strength, bending strength, bonding strength, thermal expansion coefficient, and durability performance such as chloride diffusion, carbonation, chemical attack, and steel corrosion rate. On the basis of this study, the optimal repair material which is proper to the environment condition can be selected and service life of creek concrete structures can be extended. As a result, the life cycle cost can be reduced and the waste of material resources will be cut down.

• Structural Engineering and Mechanics
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• 제71권6호
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• pp.643-656
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• 2019

A new seismic design methodology was proposed for precast concrete diaphragms. This methodology adopts seismic design factors applied on top of current diaphragm design forces. These factors are aimed to produce diaphragm design strengths aligned with different seismic performance targets. These factors were established through extensive parametric studies. These studies used a simple evaluation structure with a single-bay rectangular diaphragm. The simple evaluation structure is suitable for establishment of the design factors over comprehensive structural geometry and design parameters. However, the application of the design factors to prototype structures with realistic layouts requires further verification and investigation. This paper presents diaphragm design of several precast concrete parking structures using the new design methodology and verification of the design factor through nonlinear dynamic time history analyses. The seismic behavior and performance of the diaphragm were investigated for the precast concrete parking structures. It was found that the design factor established for the new design methodology is applicable to the realistic precast concrete parking structures.

• Earthquakes and Structures
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• 제20권1호
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• pp.13-27
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• 2021

A new seismic design methodology has been developed for precast concrete diaphragms. Seismic design factors were used to be applied on top of diaphragm seismic design forces in the current code. These factors, established through extensive parametric studies, align diaphragm design strengths with different seismic performance targets. A simplified evaluation structure with a single-bay plan was used in the parametric studies. This simplified evaluation structure is reasonable and cost-effective as it can comprehensively cover structural geometries and design parameters. However, further verification and investigation are required to apply these design factors to prototype structures with realistic layouts. This paper presents diaphragm design of several precast concrete office buildings using the new design methodology. The applicability of the design factor to the office building was evaluated and verified through nonlinear time history analyses. The seismic behavior and performance of the diaphragm were investigated for the precast concrete office buildings. It was found that the design factor established for the new design methodology is applicable to the realistic precast concrete office buildings.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.41-42
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• 2023

The physical performance of high-strength concrete deteriorates when exposed to high temperatures such as fire. In particular, in the case of ultra-high-strength concrete, there is a high possibility of explosion due to internal water pressure and thermal expansion due to the tight internal structure. In this paper, a fire resistance certification test was conducted for field application of ultra-high-strength fire-resistant concrete, and the fire resistance performance (temperature rise of main rebar) was compared according to the structural concrete cover thickness. As a result, when the covering thickness was 40 mm, three structures did not meet the certification standards, and when the covering thickness was 50 mm, all structures met the fire resistance certification standards.

• 대한토목학회논문집
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• 제33권3호
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• pp.843-854
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• 2013

이 논문에는 PS강연선이 부식된 PSC보부재의 극한휨거동을 평가하기 위해 수행한 실험연구를 수록하였다. 프리스트레스 감소와 PS강연선의 단면적 감소가 PSC보의 휨강도에 미치는 영향을 평가하기 위해 5개의 PSC보부재를 이용하여 정적하중 재하실험을 수행하였다. 두 개의 PSC보부재는 드릴을 이용해 덕트 내부에 있는 PS강연선 표면을 노출시킨 후 부식촉진장치를 이용해 인위적으로 PS강선들을 부식시켰다. 실험부재의 파괴시까지 정적하중을 재하하면서 철근과 콘크리트의 변형률, 그리고 중앙부의 처짐량 변화를 측정하였으며 또한 음향센서를 콘크리트표면에 부착하여 부식된 PS강선의 파단을 모니터링하였다. 실험결과를 토대로 PS강선이 부식된 PSC보부재의 휨강도 평가방법을 분석하였다. 또한, 사용하중 작용시 후긴장된 PSC보부재 내부의 PS강연선의 부식 여부를 조기 예측할 수 있는 방법을 고찰하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제19권3호
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• pp.30-38
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• 2015

적설한랭지의 경우, 동절기의 동해 및 적설에 의한 교통통행의 원활을 기하기 위하여 제설제를 사용한다. 이와 같은 제설염의 사용은 동결융해 및 염화물에 의해 콘크리트의 급속한 스케일링 피해를 야기시킨다. 이에 대한 피해로 인하여 콘크리트 포장은 콘크리트의 피복두께 감소에 따른 조기 열화 및 사용자의 안정성 등 여러 가지 문제를 발생시킨다. 이에 따라 국외적으로 이와 같은 현상에 대하여 평가를 하기 위해 다양한 시험 및 평가 방법이 제시되고 있다. 하지만 국내에서는 아직 평가방법에 대한 규정은 없으며, 관련 연구 또한 미미한 수준이다. 따라서 본 논문에서는 각 기관 및 나라에서 제시되고 있는 평가방법을 조사하고, 각각의 규정에 따라 실험을 수행하여 결과를 도출하여 비교 분석하였다. 나아가 이와 같은 실험방법과 실험결과의 고찰을 통하여 국내현장에 맞는 실험법을 제안하고자 한다.

• Computers and Concrete
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• 제24권6호
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• pp.541-553
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• 2019

Alkali-silica reaction (ASR) in concrete can induce degradation in its mechanical properties, leading to compromised serviceability and even loss in load capacity of concrete structures. Compared to other properties, ASR often affects the modulus of elasticity more significantly. Several empirical models have thus been established to estimate elastic modulus reduction based on the ASR expansion only for condition assessment and capacity evaluation of the distressed structures. However, it has been observed from experimental studies in the literature that for any given level of ASR expansion, there are significant variations on the measured modulus of elasticity. In fact, many other factors, such as cement content, reactive aggregate type, exposure condition, additional alkali and concrete strength, have been commonly known in contribution to changes of concrete elastic modulus due to ASR. In this study, an artificial intelligent model using artificial neural network (ANN) is proposed for the first time to provide an innovative approach for evaluation of the elastic modulus of ASR-affected concrete, which is able to take into account contribution of several influence factors. By intelligently fusing multiple information, the proposed ANN model can provide an accurate estimation of the modulus of elasticity, which shows a significant improvement from empirical based models used in current practice. The results also indicate that expansion due to ASR is not the only factor contributing to the stiffness change, and various factors have to be included during the evaluation.

• 한국구조물진단유지관리공학회 논문집
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• 제26권5호
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• pp.74-85
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• 2022

이 논문의 목적은 MCE를 적용한 콘크리트 중력식 댐의 동적소성해석에 의한 내진성능평가 수행 시 입력변수, 성능수준 평가 방법에 대한 현행 기준의 적용성을 검토하고 개선안을 제시하는 것이다. 이를 위하여 국내 콘크리트 중력식 댐을 대상 시설로 선정하여 다양한 조건으로 동적소성해석을 수행하였으며 입력변수인 콘크리트 인장강도, 파괴에너지 등에 대한 적용성을 검토하였다. 중력식 댐체 저면의 균열이 활동의 안정성 미치는 영향을 분석하여 저수기능 확보에 필요한 성능수준 평가 방법의 개선안을 도출하였다. 연구 결과 개선사항을 적용할 경우 MCE를 적용한 현행 내진성능평가 방법보다 합리적인 평가결과를 도출하는 효과가 있을 것이다.

• 콘크리트학회지
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• 제26권5호
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• pp.29-35
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• 2014

• 콘크리트학회지
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• 제12권6호
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• pp.97-108
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• 2000