• 비파괴검사학회지
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• 제36권6호
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• pp.460-465
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• 2016

배관 구조물은 긴 길이를 가지며, 일정한 거리에 위치한 고정부에 설치되거나, 지중에 매설된다. 따라서 자중 또는 지반의 움직임으로 변형과 처짐이 발생하기 쉽다. 이러한 배관의 건전성 평가에는 형상 감시 기법이 매우 유용할 수 있다. 광섬유 브래그 격자 센서 (fiber Bragg grating, FBG)는 다중화의 장점이 있어 배관과 같이 긴 길이를 가지는 구조물의 여러 지점에서 변형률 측정에 매우 유용하다. 본 연구에서는 배관의 건전성 평가를 위하여 변형률 기반의 형상추정기법을 제안하였다. 제안된 기법의 유용성을 확인하기 위하여 실험을 통한 검증을 수행하였다. 실험 결과 제안된 FBG를 이용한 형상추정기법이 시험편의 변형에 따라 유사한 형상을 표현할 수 있음을 확인하였다. 또한, 형상추정기법을 통해 도출된 처짐량이 실제 배관에 가해진 처짐과 동일하게 계산됨을 확인하였다.

• 한국해양공학회지
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• 제34권3호
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• pp.194-201
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• 2020

In this study, an optical-fiber sensor was used to measure loads that could act in an environment similar to the loading conditions that exist in an actual pipe. The structure and the installation method of the optical-fiber strain sensor were applied considering the actual large pipe and the buried pipe environment. Load tests were performed using a displacement sensor and sandbags to determine the deflection of the pipe according to the external load, and the linear measurement results were verified. Considering the conditions that could exist in the actual pipe, the test method was presented, and the strain of the buried pipe generated at this time was measured.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3745-3765
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• 2022

The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20-70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.