ABSTRACT

Based on the evolution law of ice conditions under climate change scenarios, this paper explored ice-induced vibration of the structures of offshore wind turbine in a certain area of Liaodong Bay. Firstly, the probability fitting analysis was performed with the data of sea ice extents (5 levels) from 1950 to 2018 under different scenarios. Secondly, the ice thickness probability density function of the sea area was corrected based on the analysis result. Thirdly, the numerical simulation of wind turbine structure was carried out and the dynamic ice forces of the wind power infrastructure was determined according to the ice force function for the transient dynamic analysis. The simulation results indicated found that climate change had a direct impact on the attenuation of ice conditions. Due to the decreased sea ice extent, the fatigue life of engineering structures in the study sea area was increased by 1.86%.

INTRODUCTION

Accurate reliability assessment is important in the planning, design and safe operation of ocean engineering structure in ice covered areas. In recent years, with the development of the marginal oilfields in the Liaodong Bay, economic indicators are the main indicators to be considered in the structural strength design of platforms. If the designed values of sea ice parameters are too low, the structure in ice area will be frequently exposed to great risks; if the designed values of sea ice parameters are too high, the production cost will be significantly increased. Therefore, it is necessary to reduce the engineering cost in the design of marine projects under the premise of meeting the structural strength. In general, the control load of offshore engineering structures in the ice-covered area is ice load, so the alternating stress caused by ice sheet in front of marine structures is an important factor of structural fatigue failures. The indicators influencing the structural stress are ice thickness and ice velocity. Ice condition data used in previous assessments of marine structures were basically collected in the 20th century. However, compared with the 20th century, climate change in the 21st century has attenuated the overall ice situation in China's seas in the past 20 years (LIU Yongqing, 2017). Therefore, it is necessary to evaluate the reliability of offshore engineering structures based on the ice data in recent years.

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