• 한국구조물진단유지관리공학회 논문집
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• 제2권4호
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• pp.186-193
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• 1998

The purpose of this research is to seek properties of flowing light-weight aggregate concrete and possibility of application. The experimental analysis results by using light-weight aggregate and industrial waste such flyash, furnace slag are as follow. 1) The research shows that flowing light-weight aggregate concrete of slump 23~27cm, slump flow 58~69 cm is possible, but material segregation is appeared above slump 26.5cm and slump flow 65 cm. 2) If mixing ratio of flyash is increase, strength deterioration is about 25 % in early age. It showed that effectiveness of long time strength improvement because strength manifestation ratio is above 95% in a long term. 3) This research showed possibility of substitution of blast furnace slag because strength deterioration by using mixing of furnace slag was appeared small deterioration range as below 10 %. 4) Each experimental compressive strength ratios were 77 %(1st week), 86 %(2nd week), 109 %(8th week), 115 %(13th week), 125 % (26th week) on the basis of 28 days. If mixing ratio of flyash is increase, long term strength increase ratio is improved.

• 한국구조물진단유지관리공학회 논문집
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• 제14권1호
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• pp.71-77
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• 2010

콘크리트 구조물은 여러 가지 열화현상으로 내구성 및 건전성이 크게 저하되므로, 열화현상을 억제하는 것이 중요하다. 본 연구에서는 콘크리트의 열화현상을 억제하여 성능을 개선 시킬 수 있는 경제적이고 효율적인 표면침투제의 사용방법을 도출하기 위하여 표면침투제의 종류, 농도, 함침시간을 달리한 시험체의 점도, 표면장력, 압축강도, 내약품성, 내흡수량 및 염소이온 침투저항성 시험결과를 고찰하였다. 그 결과, 콜로이달 실리카 용액 및 소듐 알루미나 실리케이트 용액의 적정 희석 농도와 함침시간은 각각 15%, 5분 및 17%, 10초로 나타났다.

• Computers and Concrete
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• 제15권6호
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• pp.879-902
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• 2015

The remaining service life (RSL) of buildings has been an important issue in the field of building and facility management, and its development is also one of the essential factors for achieving sustainable infrastructure. Since the estimation of RSL of buildings is heavily affected by the subjectivity of individual inspector or engineer, much effort has been placed in the development of a rational method that can estimate the RSL of existing buildings more quantitatively using objective measurement indices. Various uncertain factors contribute to the deterioration of the structural performance of buildings, and most of the common building structures are constructed not with a single structural member but with various types of structural components (e.g., beams, slabs, and columns) in multistory floors. Most existing RSL estimation methods, however, consider only an individual factor. In this study, an estimation method for RSL of concrete buildings is presented by utilizing a fuzzy theory to consider the effects of multiple influencing factors on the deterioration of durability (e.g., concrete carbonation, chloride attack, sulfate attack), as well as the current structural condition (or damage level) of buildings.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.195-201
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• 2008

When reinforced concrete is subjected to high temperature as in fire, there is deterioration in its properties of particular importance are loss in compressive strength, cracking and spalling of concrete, destruction of the bond between the cement paste and the aggregates and the gradual deterioration of the hardend cement paste. Assessment of fire-damaged concrete usually starts with visual observation of color change, cracking and spalling of the surface. In this paper, it was reported the trends of research and practical use on the Explosive Spalling Properties of the High-Strength Concrete.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.280-284
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• 2005

Existing construction materials such as concrete and steel have chronic problems; deterioration and corrosion. Owing to its special features of light weight ‘ high durability, anti-corrosion, composite material used in civil infrastructure can not only solve fundamental problems of deterioration and corrosion, but also reduce both construction and maintenance cost significantly. After the fabrication of deck panel with snap-fit connection by pultrusion through composite design according to stacking sequence of composite laminates and structural analysis, performance of decks will be verified and evaluated by structural tests.

• Structural Engineering and Mechanics
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• 제7권1호
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• pp.69-80
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• 1999

The purpose of this study is to propose an analytical model for the simulation of the hysteretic behavior of RC (reinforced concrete) beam-column subassemblages under various loading histories. The discrete line element with inelastic rotational springs is adopted to model the different locations of the plastic hinging zone. The hysteresis model can be adopted for a dynamic two-dimensional inelastic analysis of RC frame structures. From the analysis of test results it is found that the stiffness deterioration caused by inelastic loading can be simulated with a function of basic pinching coefficients, ductility ratio and yield strength ratio of members. A new strength degradation coefficient is proposed to simulate the inelastic behavior of members as a function of the transverse steel spacing and section aspect ratio. The energy dissipation capacities calculated using the proposed model show a good agreement with test results within errors of 27%.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.396-401
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• 2006

Dynamic behaviors of the impact damper are studied experimentally and numerically. In order to investigate wide range of excitation frequencies and amplitudes, a simple but high amplifying and bias-free experimental setup is designed. Experiments focused on the harsh operation condition demonstrate Accelerated mass loading which not only deteriorates the performance of the impact damper but also involves the structural resonance which should be avoided for the stability of the system. In the previous studies, instability or deterioration of the performance was reported for the off resonance frequency region. But this paper shows that the performance deterioration and structural resonances can be predicted. Using finite element modeling and analysis, accurate system parameters were derived and used for the numerical modeling employing the conservation of the momentum. Numerical study of the transient responses using 4th-order Runge-Kutta method demonstrates general performance of the system, and shows that accelerated mass loading phenomenon is deeply related with the vibration amplitudes and the mass of the auxiliary system.

• 한국구조물진단유지관리공학회 논문집
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• 제4권4호
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• pp.101-107
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• 2000

In this study, the Ground Penetrating Radar(GPR) was tested to evaluate the condition of concrete decks. Test results obtained by CPR were compared with values measured from drilled cores and damage mapping by the visual survey. It is shown that GPR can provide highly accurate measurements of layer properties of concrete decks and can map areas of deterioration in bridge decks by dielectric constants. The deck condition can be grouped into categories of "good" or "distressed". The ground penetrating radar data shows promise for producing rapid and accurate condition assessment for bridge decks. And these data can be used to evaluate highway bridge condition and make cost-effective bridge deck rehabilitation by accurately estimating the quantity of deteriorated concrete.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.367-370
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• 2015

Building deterioration reflects the degradation of basic building performance including structural performance, energy performance, durability, and safety, and it also includes perceived deterioration, which considers a user-based perspective. More than 50% of the existing buildings in Korea are over 15 years old and public buildings compose 2.5% of all buildings domestically. Therefore, there are several different problems, such as poor energy efficiency, structural performance, and safety. To address the challenges of increasing stock in deteriorated buildings, it is necessary to make decisions about reconstruction or renovation. In this study, we propose a new method to evaluate public building value with a contingent valuation method (CVM). By estimating willing-to-pay (WTP) from users of private buildings in similar situation with the public building, it is possible to compare market prices and calculate a correction factor to adjust the WTP data. Finally, we apply the correction factor to the WTP of a public building and estimate market price, willingness to pay (WTP). Finally, we apply the correction factor to willing to pay (WTP) of public building and estimate market price.

• 자원환경지질
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• 제36권5호
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• pp.365-374
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• 2003

다양한 유해성 화학물질들이 콘크리트의 설치환경에 따라 외부로부터 유입될 수 있다. 해수에 의한 콘크리트의 성능저하 현상은 해수의 다양한 화학성분에 의한 복잡한 작용이 연관되어 있다. 따라서, 본 연구에서는 주요 해수 성분의 영향으로 인한 콘크리트 성능저하에 관련된 이차광물의 형성에 따른 광물학적, 미세 구조적 변화 특성에 대하여 연구하였다. 부산경남의 해안지역의 기존 콘크리트 구조물들에서 성능저하특징을 관찰하고 콘크리트 시료를 채취하였다. 채취된 시료에 대한 암석학적분석과 XRD 및 SEM/EDAX 분석을 실시하여 골재와 시멘트페이스트의 화학적, 광물학적, 미세구조적 변화를 해석하였다. NaCl, CaCl, $MgCl_2$ 및 $Na_2SO_4$용액을 사용한 실내 콘크리트 변질 실험을 실시하였다. 변질실험 결과를 기존 콘크리트 시료에 대한 분석 결과를 비교함으로서 해수의 주성분들이 콘크리트의 성능저하에의 영향과 메커니즘을 분석하였다. 해수의 알칼리성분들은 알칼리-골재 반응을 가속화하며, 콘크리트의 심한 팽창과 균열을 발생하는 알칼리-칼슘-실리카겔을 형성하는 것으로 나타났다. 탄산화작용은 다량의 비교결성의 방해석을 형성하여 시멘트페이스트를 약화시키고 있다. 또한, 탄산화작용은 그 진행 정도에 따라 일부 이차광물들의 성분과 안정도에 현저한 영향을 미치는 것으로 나타났다. 탄산화가 현저히 진행된 콘크리트에는 다량의 석고가 형성되었으나, 탄산화가 약하게 진행된 것에는 사우마사이트가 에트린자이트와 고용체를 형성하여 미세 균열을 발생하고 있다. 실험적으로, 에트린자이트는 염소의 유입으로 인하여 trichloroaluminate로 전이되거나 분해되는 것으로 나타났다. 해수의 Mg 이온은 비교결성의 브루사이트와 MSH (magnesium silicate hydrate)를 형성하여 시멘트 페이스트의 성능저하의 원인이 되는 것으로 나타났다.