Session: 02-11-01 Fatigue and Fracture Reliability

Submission Number: 156360

Fatigue Reliability Assessment of Floating and Bottom-Fixed Offshore Wind Turbines 

The primary aim of designing offshore structures is to guarantee their safety and reliability, which involves carefully considering various environmental and economic factors. To achieve this, it is essential to utilize comprehensive and representative environmental data alongside sophisticated models that accurately evaluate the resulting loads and structural responses. A detailed understanding of meteorological conditions, such as wind, wave and current influences, is critical for the fatigue design of offshore wind turbines. This knowledge is pivotal in optimizing the performance and longevity of these structures in the challenging marine environment. This study investigates the fatigue reliability of important structural components in offshore wind turbines. It emphasizes the significance of various design fatigue factors that critically influence the longevity and performance of these systems. The fatigue reliability of several key areas, including the blade root, critical tubular members, and the tower base of the OC4 jacket wind turbine, the OC4 semi-submersible wind turbine, the OC6 TetraSpar, as well as the mooring lines are investigated. A key aspect is the definition of the Fatigue Limit State failure event, which serves as a benchmark for evaluating structural integrity under cyclical loading conditions. Various sources of uncertainty that can significantly influence these failure events, affecting the overall performance and safety of the wind turbines, are assessed and discussed.

Presenting Author: Hadi Amlashi University of South-Eastern Norway

Presenting Author Biography: Dr. Hadi Amlashi, PhD in Marine Structures, is an Associate Professor in Structural Engineering at the University of South-Eastern Norway. His main specialities cover Buckling, Ultimate Strength and Fatigue Limit State Design, Advanced Nonlinear Finite Element Analysis, Structural Reliability Analysis and Probabilistic Code Calibration. He has contributed to many research projects developing advanced numerical models for various structural systems and semi-probabilistic design format and has a vast amount of engineering experience from industry with the application in various fields ranging from fixed and floating offshore and marine structures to the subsea oil and gas operation, transportation and exploration systems (subsea structures and pipelines, subsea
wellhead systems, etc). He has published in several peer-reviewed journals and conference proceedings in marine and offshore structures and contributed to many inhouse design practices in the industry. He has served in the Ultimate Strength committee of the International Ship and Offshore Structures Congress (ISSC) for the period of 2009-2012 and is currently a member in committee IV.1 “Design Methods, Principles and Criteria” for the period of 2022-2025. He has been on the evaluation committee for the revision update of the NORSOK Standard U-001 2021 “Subsea Production Systems” for the period of 2018-2020. He has also served as peer reviewer of several
journals, such as Marine Structures and Ocean Engineering.