Seismic Reliability Analysis of Offshore Wind Turbine Jacket Structure Using Stress Limit State

Considering the effect of dynamic response amplification, a reliability analysis of an offshore wind turbine support structure under an earthquake is presented. A reliability analysis based on the dynamic response requires a large amount of time when using not only a level 3 approach but also level 2 such as a first order reliability method (FORM). Moreover, if a limit state is defined by using the maximum stress at a structural joint where stress concentration occurs, a three-dimensional element should be used in the finite element analysis. This makes the computational load much heavier. To deal with this kind of problem, two techniques are suggested in this paper. One is the application of a quasi-static structural analysis that takes the dynamic amplification effect into account. The other is the use of a stress concentration factor to estimate the maximum local stress. The proposed reliability analysis is performed using a level 2 FORM and verified using a level 3 simulation approach. Received 2 February 2016, revised 10 June 2016, accepted 18 August 2016 Corresponding author Dong-Hyawn Kim: +82-63-469-1862, welcomed@naver.com ◯c 2016, The Korean Society of Ocean Engineers It is noted that this paper is revised edition based on proceedings of KSCE 2015 Convention in Kunsan.