Abstract Monopile offshore wind turbines (MOWT) are inserted into sea water and sea bed soil. As the piles are usually embedded into the soil as deep as about 40 m, dynamic pile-water and pile-soil interactions, as well as seismic excitation non-uniformity, often occur under earthquake. In this paper, the response spectrum method (RSM) is developed to calculate the maximum response of MOWT considering the pile-water and pile-soil interactions subjected to the non-uniform seismic excitation. The tower and pile are modeled by Timoshenko beam elements, with both nacelle and rotor including hub and blades integrated as a lumped mass at the top of the tower. The pile-water and pile-soil interactions are considered by added mass and soil spring at their interfaces, respectively. The non-uniform seismic excitation is obtained by the site transfer function from the horizontal earthquake motions or design response spectrum at the water-soil interface. The seismic analysis model is solved by using a multiple-support RSM under design response spectrum. Seismic responses of a case of 5-MW MOWT on two types of soil sites are analyzed. The results indicate that the pile-water and pile-soil interactions and seismic excitation non-uniformity should be considered in analyzing such seismic problems of MOWT, while the RSM can be an effective tool.

中文翻译：

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单桩海上风电机组抗震分析的响应谱方法

摘要 单桩海上风力涡轮机（MOWT）被插入海水和海床土壤中。由于桩通常埋入土层深达40 m左右，因此在地震作用下，常发生桩-水、桩-土的动力相互作用以及地震激励的不均匀性。在本文中，考虑到非均匀地震激发下的桩-水和桩-土相互作用，开发了响应谱法 (RSM) 来计算 MOWT 的最大响应。塔和桩采用 Timoshenko 梁单元建模，机舱和转子包括轮毂和叶片，集成为塔顶的集总质量。桩-水和桩-土相互作用分别通过其界面处的附加质量和土弹簧来考虑。非均匀地震激发是通过场地传递函数从水土界面的水平地震运动或设计响应谱中获得的。地震分析模型是通过在设计响应谱下使用多支撑 RSM 来求解的。分析了 5 兆瓦 MOWT 对两种土壤场地的地震响应。结果表明，在分析MOWT的此类地震问题时，应考虑桩-水和桩-土相互作用和地震激励的非均匀性，而RSM是一种有效的工具。