Ocean Systems Engineering

  • 제2권2호
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  • Pages.115-135
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  • 2012
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  • 2093-6702(pISSN)
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  • 2093-677X(eISSN)
테크노프레스 (Techno-Press)
권호 표지
DOI QR코드

DOI QR Code

Response of square tension leg platforms to hydrodynamic forces

  • Abou-Rayan, A.M. (Civil Engineering Tec. Dept., Faculty of Engineering, Benha Univ.) ;
  • Seleemah, Ayman A. (Structural Engineering Dept., Faculty of Engineering, Tanta Univ.) ;
  • El-Gamal, Amr R. (Civil Engineering Tec. Dept., Faculty of Engineering, Benha Univ.)
  • 투고 : 2011.09.05
  • 심사 : 2012.06.07
  • 발행 : 2012.06.25
⟨ 이전 논문 다음 논문 ⟩

초록

The very low natural frequencies of tension leg platforms (TLP's) have raised the concern about the significance of the action of hydrodynamic wave forces on the response of such platforms. In this paper, a numerical study using modified Morison equation was carried out in the time domain to investigate the influence of nonlinearities due to hydrodynamic forces and the coupling effect between surge, sway, heave, roll, pitch and yaw degrees of freedom on the dynamic behavior of TLP's. The stiffness of the TLP was derived from a combination of hydrostatic restoring forces and restoring forces due to cables and the nonlinear equations of motion were solved utilizing Newmark's beta integration scheme. The effect of wave characteristics such as wave period and wave height on the response of TLP's was evaluated. Only uni-directional waves in the surge direction was considered in the analysis. It was found that coupling between various degrees of freedom has insignificant effect on the displacement responses. Moreover, for short wave periods (i.e., less than 10 sec.), the surge response consisted of small amplitude oscillations about a displaced position that is significantly dependent on the wave height; whereas for longer wave periods, the surge response showed high amplitude oscillations about its original position. Also, for short wave periods, a higher mode contribution to the pitch response accompanied by period doubling appeared to take place. For long wave periods, (12.5 and 15 sec.), this higher mode contribution vanished after very few cycles.

키워드

참고문헌

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피인용 문헌

  1. Tethers tension force effect in the response of a squared tension leg platform subjected to ocean waves vol.4, pp.4, 2014, https://doi.org/10.12989/ose.2014.4.4.327
  2. Wave induced motion of a triangular tension leg platforms in deep waters vol.3, pp.2, 2013, https://doi.org/10.12989/ose.2013.3.2.149