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남진원 ( Nam Jin-won ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
In this research, the measurement of vibration for stay-cable installed in cable stayed bridge was carried out by using wireless accelerometer. The vibration measurement data can be used for the evaluation of safety and serviceability of cable stayed bridge. The acquired data was analyzed for the evaluation of maximum vibration, tension force and fatigue. To verify the reliability of data, the additional measurements with total station and video camera. The data from three different measurement methods showed similarity within 15 % gap.
남진원(Nam Jin Won),김호진(Kim Ho Jin),김성배(Kim Sung Bae),변근주(Byun Keun Joo) 대한토목학회 2007 대한토목학회논문집 A Vol.27 No.3A
폭발하중은 매우 빠른 시간 내에 구조물에 큰 압력으로 작용하는 하중이므로 변형률 속도와 구조물의 국부적인 손상을 고려하여 동적응답을 평가해야한다. 그러나 폭발하중을 받는 구조물의 설계 및 해석에 일반적으로 사용되고 있는 기존의 근사적 해석기법은 폭발하중에 대한 경계조건과 동적재료특성을 정확하게 반영하지 못할 뿐 아니라 폭발하중을 받는 구조물이 나타내는 국부적인 거동을 나타내지 못한다. 또한 근사적 해석기법 결과의 정확도와 신뢰성에 대한 문제는 꾸준히 지적되어오고 있다. 게다가 동적하중에 대한 콘크리트와 철근의 응답은 정적하중에 대한 응답과 상이하므로 폭발하중에 대한 응답을 계산하는데 있어 정적하중이나 준정적하중상태로 정의되는 재료 모델을 사용하는 것은 적합하지 않다. 따라서, 본 연구에서는 폭발하중에 대한 콘크리트 구조물의 동적거동을 예측하기 위해 물리적 현상에 충실하는 정밀해석 방법인 HFPB(high fidelity physics based) 해석방법을 사용하였다. HFPB 해석을 위해서는 양함수적(explicit) 유한요소 코드인 LS-DYNA가 사용되었고, 해석결과의 비교를 위해서 단자유도 시스템 해석이 수행되었다. 해석결과를 통해 HFPB 해석방법은 단자유도 해석방법에 비해 합리적인 결과를 나타내며, 단자유도 해석방법은 경우에 따라 구조물의 성능을 과대 또는 과소평가할 수도 있는 것으로 분석되었다. 따라서, 정확하고 상세한 방호성능의 평가 및 설계가 요구되는 경우에는 적합한 재료모델을 사용하는 정밀해석 방법이 필요할 것이다. As blast load is impulsive load of extremely short duration with very high pressure, the strain rate and local damage effect of concrete structures subjected to blast loads should be considered in the dynamic analysis. However, the approximate and simplified analysis techniques, which have been generally used in the design and analysis of structures subjected to blast load, cannot accurately consider effect of boundary conditions and dynamic material properties. Problems on the accuracy and reliability of approximate analysis results have also been pointed out. In addition, as the response of concrete and reinforcement on dynamic load is different from that on static load, it is not appropriate to the use material model defined in the static or quasi-static conditions in calculating the response on the blast load. Therefore, this study suggest the dynamic analysis method using high fidelity physics based (HFPB) analysis to predict damage and failure of a concrete structure under the blast loading condition. The explicit finite element code LS-DYNA is adopted for HFPB analysis and single-degree-of-freedom (SDOF) system is used for comparison of results. From the analysis results, it is found that HFPB analysis could represent reasonable results compared to those of SDOF analysis and SDOF analysis might overestimate or underestimate the resistance of structure under blast load. In case of detailed analysis, HFPB analysis with proper material model is needed to evaluate the resistance of structure correctly.
건축물의 케이블 월 시스템의 케이블 장력 관리 및 장기 거동 분석
남진원 ( Nam Jin-won ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
In the cable wall system, the cable tension force can be changed by the various reasons. After 10 years from the construction of cable wall system in Hamad Medical City Womens Hospital of Qatar, an average of about 16% of the tension force was decreased. Since the tension loss can affect the structural capacity and stability, the re-tightening was carried out up to about 90% of the design tension. Also, the annual regular inspection including the measurement of cable tension is proposed as the maintenance plan.
사장교 케이블 진동 데이터를 이용한 케이블 감쇠비 산정 자동화 프로그램 개발
남진원 ( Nam Jin-won ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
In this study, the damping ratio was estimated using the developed automatic calculation software based on the field measurement data of vibration of stay cable in cable-stayed bridge. For the field measurement, two accelerometers were used for obtaining of dynamic behavior of 1st, 2nd and 3rd mode. The damping ratio after installation of the damper was calculated as higher than the requirement values, also it was confirmed that the damping effect was improved with the range of 19~92%.
LoRa 무선통신 기반의 데이터수집장치 개발 및 현장 계측에 대한 적용성 평가
남진원 ( Nam Jin-won ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
In this study, prototype DAU with LoRa wireless communication module is designed and manufactured. Also, the customized software is developed for the automatic data transmission to end-user from ThingPlug server of SK telecom LoRa network. For verification of the developed wireless monitoring system, DAU was installed on bridge construction site. The reliability of data and operational stability was evaluated by comparison with data from conventional monitoring system.
WIM 계측데이터를 활용한 포장체의 공용 수명 예측 알고리즘 개발
남진원 ( Nam Jin-won ) 한국구조물진단유지관리공학회 2019 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.23 No.1
The statistical data from WIM has been used only for traffic management and fatigue evaluation of structures. In this study, the algorithm using ESAL for assessment of pavement condition is proposed. To verify the algorithm, WIM system using PVDF sensor was installed on the pavement of bridge deck, also the automatic assessment software was developed. For the reliability verification of the alogorithm, further comparative study based on the long-term data is needed.