With high flexibility and low damping, offshore wind turbines (OWTs) are prone to external vibrations such as wind, wave and earthquake, either attacked individually or as combined loading cases. This study proposes a semi-active variable-stiffness tuned mass damper (VSTMD) with magnetorheological elastomer (MRE) materials to mitigate undesired dynamic responses of OWT. A jacket supported OWT with MRE-TMD installed at the top of the tower is adopted as an example to demonstrate the effectiveness of the proposed design under multiple hazards. A semi-active frequency tracing algorithm is proposed through which the current-dependent stiffness of MRE-TMD is controlled by tracking the acceleration of OWT tower. The numerical results demonstrate that the semi-active MRE-TMD can effectively attenuate the dynamic responses of OWT under multi-hazard loadings, and it outperforms the passive TMD in reducing the peak and RMS displacements of tower structure. Robustness analysis of semi-active MRE-TMD is also validated by considering OWT sudden loss of partial stiffness under multiple-loadings.

海上风力涡轮机 (OWT) 具有高灵活性和低阻尼特性，容易受到风、波浪和地震等外部振动的影响，无论是单独攻击还是组合载荷情况。本研究提出了一种半主动可变刚度调谐质量阻尼器 (VSTMD)，采用磁流变弹性体 (MRE) 材料来减轻 OWT 的不良动态响应。以塔顶安装有 MRE-TMD 的导管架支撑 OWT 为例，证明了该设计在多种危险下的有效性。提出了一种半主动频率跟踪算法，通过跟踪OWT塔的加速度来控制MRE-TMD的电流相关刚度。数值结果表明，半主动 MRE-TMD 可以有效衰减 OWT 在多灾害载荷下的动态响应，并且在降低塔结构峰值位移和 RMS 位移方面优于被动 TMD。半主动 MRE-TMD 的鲁棒性分析也通过考虑多载荷下 OWT 突然失去部分刚度来验证。