Journal of the Computational Structural Engineering Institute of Korea (한국전산구조공학회논문집)

Computational Structural Engineering Institute of Korea (한국전산구조공학회)
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Evaluation of Structural Response of Cylindrical Structures Based on 2D Wave-Tank Test Due to Wave Impact

파랑충격력에 의한 원형실린더구조물의 구조응답평가

  • Lee, Kangsu (Korea Research Institute of Ships & Ocean Engineering) ;
  • Ha, Yoon-Jin (Korea Research Institute of Ships & Ocean Engineering) ;
  • Nam, Bo Woo (Department of Naval Architecture & Ocean Engineering, Seoul National University) ;
  • Kim, Kyong-Hwan (Korea Research Institute of Ships & Ocean Engineering) ;
  • Hong, Sa Young (Korea Research Institute of Ships & Ocean Engineering)
  • 이강수 (선박해양플랜트연구소 해양플랜트에너지연구본부) ;
  • 하윤진 (선박해양플랜트연구소 해양플랜트에너지연구본부) ;
  • 남보우 (서울대학교 조선해양공학과) ;
  • 김경환 (선박해양플랜트연구소 해양플랜트에너지연구본부) ;
  • 홍사영 (선박해양플랜트연구소 해양플랜트에너지연구본부)
  • Received : 2020.04.22
  • Accepted : 2020.06.29
  • Published : 2020.10.31
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Abstract

The wave-impact load on offshore structures can be divided into green-water and wave-slamming impact loads. These wave impact loads are known to have strong nonlinear characteristics. Although the wave impact loads are dealt with in the current classification rules in the shipping industry, their strong nonlinear characteristics are not considered in detail. Therefore, to investigate these characteristics, wave-impact loads induced by a breaking wave on a circular cylinder were analyzed. A model test was carried out to measure the wave-impact loads due to breaking waves in a two-dimensional (2D) wave tank. To generate a breaking wave, the focusing wave method was applied. A series of 2D tank tests under a horizontal wave impact was carried out to investigate the structural responses of the cylindrical structure, which were obtained from the measured model test data. According to the results, we proposed a structural damage-estimation procedure of an offshore tubular member due to a wave impact load. Furthermore, a recommended wave-impact load is suggested that considers the minimum required thickness of each member. From the experimental results, we found that the required minimum thickness is dependent on the impact pressure located in a three-dimensional space on the surface of a tubular member.

본 연구에서는 2D 조파수조를 통해 수행된 모형시험결과를 기반으로 원형실린더에 분포하는 파랑충격압력을 시간에 따라 계측하고 이를 CFD해석 결과와 비교하였다. 전산유체역학 해석을 통해 파랑충격력에 직접평가법에 관한 효용성을 확인할 수 있었고, 실험으로부터 구한 파랑충격 시계열 데이터를 그대로 원형단면을 갖는 실제 해양구조물의 부재에 적용하였다. 실린더에 분포하는 변위 및 응력의 특성과 특이점이 바뀌는 것을 확인하였고 실제 시계열을 적용하는 것이 해양구조물의 강도평가를 보다 정확하게 평가할 수 있음을 확인할 수 있었다. 또한, 선수부에 요구되는 외판의 최소선급규정에 따른 두께 경험식들을 분석하여 적용하고자 하였다. 동일한 재료 물성치를 갖는 강재에 관해 선수외판에 요구되는 구조물의 최소두께와 원형단면 부재에 요구되는 최소두께를 비교·분석하였고 이를 통해 NORSOK standard에 제시되어 있는 구조물의 손상기준을 활용하여 허용 두께치를 추정하고자 하였다. 특히 해양구조물의 갑판충격력(wave in deck)의 경우 이와 관련된 경험식이나 최소두께 요구사항들이 정립되어 있지 않기 때문에 본 연구를 통해 파랑충격력에 따라 요구되는 판재의 최소두께를 제안하고자 하였다.

Keywords

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