• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.275-276
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• 2009

본 논문에서는 중성화에 노출된 콘크리트 구조불의 내구성을 예측하기 위한 새로운 접근 방법을 제시한다. 이 예측 방법은, 새로운 계측 데이터 있을 때 베이스 이론에 근거하여 지속적으로 업데이팅 을 할 수 있다. 모델 매개변수의 확률론적인 특성이 고려된다. 염해 해석 모델의 절차는 라틴 하이퍼 큐브 샘플 추출법으로 간단하게 정리되고 이를 통해 얻는 표본으로 결정된다. 이러한 새로운 방법은 중요한 콘크리트 구조물을 설계하기에 아주 유용하고 모니터링을 통한 실 콘크리트 구조물의 잔존수명을 예측 할 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.114-119
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• 2004

Endbeam is an important structural member of freight bogie for the support of service loading. In general, more than 25 years' durability is necessary. However, endbeam occur fatigue fracture in dynamic stress concentration location because comparatively strength and stiffness are low. Therefore, structure analysis is performed to evaluate structural problem of endbeam and local strain range as durability analysis. The number of cycles is extracted concerning the bogie in operation by measurement dynamic stress time history on critical part which is crack initiation in actual fact. At this time rainflow cycle counting is used to consider change of stress for operating condition. Based on the fatigue life curves and the stress analysis, the fatigue life of the endbeam is predicted and compared with the experimentally determined fatigue life, resulting in a fairly good correlation.

• Computers and Concrete
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• 제6권4호
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• pp.281-303
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• 2009

The lack of safety of bridge deck structures causes frequent repair and strengthening of such structures. The repair induces great loss of economy, not only due to direct cost by repair, but also due to stopping the public use of such structures during repair. The major reason for this frequent repair is mainly due to the lack of realistic and accurate assessment system for the bridge decks. The purpose of the present research was to develop a realistic expert system, called Bridge Slab-Expert which can evaluate reasonably the condition as well as the service life of concrete bridge decks, based on the deterioration models that are derived from both the structural and environmental effects. The diagnosis assessment of deck slabs due to structural and environmental effects are developed based on the cracking in concrete, surface distress and structural distress. Fuzzy logic is utilized to handle uncertainties and imprecision involved. Finally, Bridge Slab-Expert is developed for prediction of safety and remaining service life based on the chloride ions penetration and fick's second law. Proposed expert system is based on user-friendly GUI environment. The developed expert system will allow the correct diagnosis of concrete decks, realistic prediction of service life, the determination of confidence level, the description of condition and the proposed action for repair.

• 한국구조물진단유지관리공학회 논문집
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• 제14권4호
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• pp.126-132
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• 2010

탄산화는 콘크리트 내부의 알칼리성 수화생성물과 대기 중의 탄산가스가 반응하는 것을 의미하며, 탄산화에 의한 철근부식은 철근 콘크리트의 내구성을 저하시키는 주요원인 중의 하나이다. 본 논문에서는 국내에서 광범위하게 시공된 교량구조물에 대한 실태조사를 이용하여 교량구조물이 위치한 환경에 따른 탄산화의 영향을 파악하였다. 또한 계측결과들을 바탕으로 탄산화에 의한 구조물의 내구적 파괴확률을 신뢰성 이론을 기반으로 하여 분석하고, 국내 시방서에서 제시하는 목표파괴확률을 기준으로 대상구조물의 내구수명을 평가하였다. 현장실험결과를 토대로 한 탄산화의 분석결과 교량의 사용년수가 증가함에 따라 탄산화 깊이는 증가함을 보였으며, 교량구조물의 탄산화 속도 분석결과 하천교량에 비하여 도심지 및 해상 교량의 탄산화 속도가 1.6-1.9배 빠르게 나타났다. 또한, 교량구조물의 내구수명을 파악한 결과 하천 교량에 비하여 도심지 및 해상 교량의 내구수명은 약 2.4-3.3배 적게 나타났다.

• 한국자동차공학회논문집
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• 제6권5호
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• pp.146-152
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• 1998

Recently, for the development of vehicle structures and components there is a tendency to increase using numerical simulation methods compared with practical tests for the estimation of the fatigue strength. In this study, an integrated powerful methodology is suggested for fatigue strength evaluation through development of the interface program to integrate dynamic analysis quasi-static stress analysis and fatigue analysis, which were so far used independently. To verify the presented evaluation method, a single and zigzag bump run test, 4-post road load simulation and driving durability test have been performed. The prediction results show a good agreement between analysis and test. This research indicates that the integrated life prediction methodology can be used as a reliable design tool in the pre-prototype and prototype development stage, to reduce the expense and time of design iteration.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.291-292
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• 2009

본 연구에서는 염해환경하에 있는 콘크리트 구조물의 균열 발생 및 피복콘크리트의 탈락에 대한 내구성 한계상태를 설정하여 내구 수명해석을 수행하였다. 본 연구에서 사용된 부식개시이후의 수명해석 방법은 부식에 따른 콘크리트 구조물의 내구성과 그에 따른 사용성 저하를 정량적으로 평가하는 되 유용하게 사용될 수 있다.

• 한국공간구조학회논문집
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• 제20권4호
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• pp.111-121
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• 2020

There has been increasing interest in UHPC (Ultra-High Performance Concrete) materials in recent years. Owing to the superior mechanical properties and durability, the UHPC has been widely used for the design of various types of structures. In this paper, machine learning based compressive strength prediction methods of the UHPC are proposed. Various regression-based machine learning models were built to train dataset. For train and validation, 110 data samples collected from the literatures were used. Because the proportion between the compressive strength and its composition is a highly nonlinear, more advanced regression models are demanded to obtain better results. The complex relationship between mixture proportion and concrete compressive strength can be predicted by using the selected regression method.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.58-59
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• 2020

The change of temperature and humidity in early-age concrete has a great influence on the durability of the structure. In this study, a reliable wireless sensor network system and a concrete embedded type Compressive strength prediction sensor were designed using the Arduino platform. The accuracy of the compressive strength prediction sensor was verified through a mock-up experiment, and it was confirmed that the experiment had sufficient accuracy to be used in the field environment.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.921-938
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• 2015

Realistic prediction of concrete creep is of crucial importance for durability and long-term serviceability of concrete structures. To date, research about the behaviour of self-compacting concrete (SCC) members, especially concerning the long-term performance, is rather limited. SCC is quite different from conventional concrete (CC) in mixture proportions and applied materials, particularly in the presence of aggregate which is limited. Hence, the realistic prediction of creep strains in SCC is an important requirement for the design process of this type of concrete structures. This study reviews the accuracy of the conventional concrete (CC) creep prediction models proposed by the international codes of practice, including: CEB-FIP (1990), ACI 209R (1997), Eurocode 2 (2001), JSCE (2002), AASHTO (2004), AASHTO (2007), AS 3600 (2009). Also, SCC creep prediction models proposed by Poppe and De Schutter (2005), Larson (2007) and Cordoba (2007) are reviewed. Further, new creep prediction model based on the comprehensive analysis on both of the available models i.e. the CC and the SCC is proposed. The predicted creep strains are compared with the actual measured creep strains in 55 mixtures of SCC and 16 mixtures of CC.

• 한국수자원학회논문집
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• 제36권1호
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• pp.45-59
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• 2003

본 연구에서는 상수관의 개량사업을 보다 효율적으로 실시 할 수 있는 방법으로 국내 실정에 적합한 상수관로의 노후도 조사방법을 이용하여 매설된 관의 노후도를 예측 근거한 최적 개량 모형을 제시하였다. 노후도 예측 모형은 확률론적 신경망 이론을 바탕으로 관별 노후도 정도를 5개 등급으로 구분하며 산정된 관별 노후도 등급 및 관경을 바탕으로 최대 잔존수명을 산정하였다. 최적 개량 모형은 관의 유지보수, 갱생, 교체의 시기 및 비용을 산정하는 것으로 최단경로흐름을 응용한 정수계획법을 이용하여 제시하였다. 또한 개발된 최적 개량 모형은 보다 현실적인 모형을 구축하기 위해 예산제약 유무에 따라 2가지 구분하여 모형을 제시하였다. 따라서, 본 연구에서 제안된 모형은 상수관로의 관리를 위해 보다 정량적인 방법으로 활용할 수 있을 것이다.