Session: 02-09-01 Reliability of Moorings & Risers

Submission Number: 180774

A Framework for Ultimate Strength Based Safety Assessment of Offshore Mooring Chain 

This study aims to develop an empirical relation for directly predicting the interlink angle of mooring chain links from the global tension force and tension angle obtained in mooring system analyses. With the increasing deployment of floating offshore structures in harsh environments, ensuring the reliability and fatigue life of mooring systems has become a critical design concern for long-term structural safety. According to the current fatigue assessment guideline for mooring chains (BV NI 604), the interlink angle and bending moment of chain links must be obtained through additional nonlinear finite element analysis (FEA) based on the global analysis results. However, such procedures require significant computational time and cost, which limits their applicability in iterative design and optimization processes. To improve this process, the mooring chain geometry was simplified using beam elements, and a nonlinear FEA model consisting of 20 links was analyzed under various combinations of tension force and tension angle. The interlink angles derived from the simulations were then processed through regression analysis to establish an empirical prediction equation. The proposed relation enables rapid estimation of the interlink angle directly from global mooring analysis results, providing a practical and computationally efficient approach for fatigue assessment and enhancing the overall design efficiency of offshore mooring systems.

Presenting Author: Jun Young Jang Seoul National University

Presenting Author Biography: Jun Young Jang is a combined Master’s and Ph.D. student in the Department of Naval Architecture and Ocean Engineering at Seoul National University (SNU) and a member of the Ocean and Shore Technology (OST) research group under Professor Do Kyun Kim. His research focuses on the structural performance of mooring systems for offshore structures, including the ultimate strength and fatigue behavior of mooring chains.

Authors:

Jun Young Jang Seoul National University
Dong In Kim Seoul National University
Nak-Kyun Cho Seoul National University of Science and Technology
Woo Chul Chung National Korea Maritime & Ocean University
Binbin Li Tsinghua University
Do Kyun Kim Seoul National University