Journal of Ocean Engineering and Technology (한국해양공학회지)

Korean Society of Ocean Engineers (한국해양공학회)
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Comparison of Numerical Analyses and Model Test for Evaluation on Hydroelastic and Higher-order Springing Responses of Fixed Cylindrical Structure

  • Kim, Hyun-Sung (Offshore Platform Research Division, Korea Research Institute of Ships and Ocean Engineering) ;
  • Won, Younguk (Offshore Platform Research Division, Korea Research Institute of Ships and Ocean Engineering) ;
  • Oh, Young Jae (Offshore Platform Research Division, Korea Research Institute of Ships and Ocean Engineering) ;
  • Lee, Kangsu (Offshore Platform Research Division, Korea Research Institute of Ships and Ocean Engineering) ;
  • Kim, Byoung Wan (Offshore Platform Research Division, Korea Research Institute of Ships and Ocean Engineering)
  • Received : 2021.01.06
  • Accepted : 2021.05.28
  • Published : 2021.06.30
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Abstract

Studies on very large offshore structures are increasing owing to the development of deep sea, large-scale energy generation using ocean resources, and so on. The enlargement of offshore structures makes the hydroelastic effect and low natural frequency related responses important. Numerical analyses and model tests for hydroelastic and higher-order springing responses of fixed cylindrical structures are conducted in this study. The panel methods with and without the hydroelastic effect with shell elements, and the Morison analysis method with beam elements are applied. To observe the hydroelastic effect for structural strength, two structures are considered: bottom-fixed cylindrical structures with high and low bending stiffnesses, respectively. The surge motions at the top of the structure and bending stresses on the structure are observed under regular and irregular wave conditions. The regular wave conditions are generated considering the ratios of the cylindrical outer diameter to the wave lengths, and keeping the wave steepness constant. The model tests are performed in the three-dimensional ocean engineering basin in the KRISO (Korea Research Institute of Ships and Ocean Engineering). From the numerical and experimental results, in which the hydroelastic responses are only observed in the case of the structure with a low bending stiffness, it is confirmed that the hydroelastic responses are highly dependent on the structural stiffness. Additionally, the higher-order phenomenon on the specified wave condition is analyzed by observing the higher-order springing responses when the incident wave frequency or its multiples with the high wave height coincides with the natural frequency of the structure.

Keywords

Acknowledgement

We acknowledge that this study is part of the research conducted with support from the Korea Institute of Ships and Ocean Engineering under the project, "Core Technology Development of Hydro-elasticity based Structural Damage Assessment for Offshore Structures considering Uncertainties (Grant No. PES3930)". We appreciate the support for research funding.

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