Abstract To optimize offshore wind turbine (OWT) design, an engineering tool has been developed allowing for a detailed investigation of the effects of nonlinear soil stiffness and damping on foundation dynamics. We have studied the response of a vertically oscillating offshore wind monopile foundation in a realistic soil profile subjected to loads between 1 and 200 MN in the frequency range 0–10 Hz with pseudo-static and equivalent linear dynamic model. The non-linear soil behaviour is modelled with an equivalent linear method with shear modulus reduction and damping curves as input. The tool is verified and validated by comparison with elasto-dynamic model and experiments. With increasing load amplitudes foundation stiffness increases and damping decreases. For large load amplitudes the lower part of the pile foundation contributes more to foundation damping. The results indicate the nonlinear foundation stiffness and damping can be modelled rationally by combining stiffness and hysteretic damping from nonlinear static tools with apparent mass and radiation damping from elasto-dynamic analysis. The tool can be used to compute soil springs and dampers based on laboratory-based soil stiffness and damping.

中文翻译：

---

垂直振动单桩的等效线性拟静力和动力建模

摘要 为了优化海上风力涡轮机 (OWT) 设计，开发了一种工程工具，可以详细研究非线性土壤刚度和阻尼对基础动力学的影响。我们已经使用伪静态和等效线性动力学模型研究了在 0-10 Hz 频率范围内承受 1 到 200 MN 载荷的真实土壤剖面中垂直振荡的海上单桩基础的响应。非线性土壤行为使用等效线性方法建模，剪切模量减少和阻尼曲线作为输入。该工具通过与弹动力模型和实验的比较得到验证和验证。随着载荷幅值的增加，地基刚度增加而阻尼减小。对于大的荷载幅值，桩基础的下部对基础阻尼的贡献更大。结果表明，通过将非线性静态工具的刚度和滞回阻尼与弹性动力学分析的视质量和辐射阻尼相结合，可以对非线性基础刚度和阻尼进行合理建模。该工具可用于根据基于实验室的土壤刚度和阻尼来计算土壤弹簧和阻尼器。