A Nonlinear Response Analysis of Tension Leg Platforms in Irregular Waves

J. Ocean Eng. Technol. 1998;12(2):33-42.

Lee, Chang-Ho;Gu, Ja-Sam;Jo, Hyo-Je;Hong, Bong-Gi;

Pukyong National University;Pukyong National University;Korea Maritime University;Pukyong National University;

불규칙파중의 인장계류식 해양구조물의 비선형 응답 해석

이창호;구자삼;조효제;홍봉기;

부경대학교;부경대학교;한국해양대학교;부경대학교;

Keywords: Tension Leg Platforms, Second Order Wave Exciting Force, Resonant Response, Difference Frequency, Sum Frequency, Nonlinear Response

핵심용어: 인장계류식 해양구조물, 2차 파강제력, 공진응답, 차주파수, 합주파수, 비선형 응답

Abstract

In the presence of incident waves with different frequencies, the second order sum and difference frequency waves due to the nonlinearity of the incident waves come into existence. Although the magnitudes of the forces produced on a Tension Leg Platform(TLP) by these nonlinear waves are small, they act on the TLP at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wave loads produced close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The second order wave exciting forces and moments have been obtained by the method based on direct integration of pressure acting on the submerged surface of a TLP. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.