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为了掌握高阶振型对结构地震反应的贡献,以4座不同规模的典型风力机为研究对象,建立考虑塔顶质量转动惯量的堆聚质量动力计算模型。采用振型分解时程分析法,计算各塔架在2条实际地震波作用下的时程反应。基于瑞利阻尼假定,综合考虑结构内阻尼和气动阻尼,保守地将瑞利阻尼的两个参考振型阻尼比确定为0.5%。另外,比较了由相关国际规范和指南推荐的忽略高阶振型和塔架实际质量分布的单质量振子简化模型与该文采用的堆聚质量模型的时程分析结果。分析结果表明:风力机塔架的地震反应显著;高阶振型的贡献大小与结构自身的动力特性和地震波的选取有关;高阶振型对风力机塔架的位移、塔顶加速度影响不大,对塔架弯矩具有一定影响,对剪力反应的影响较为显著;时程分析时,单质量振子简化模型会得到偏于不安全的地震反应结果。
In order to grasp the contribution of high-order vibration modes to the seismic response of structures, four typical wind turbines of different sizes were taken as the research object, and a model of mass-momentum calculation was established to consider the mass moment of inertia of the tower top. The modal decomposition time history method is used to calculate the time-history response of each tower under the action of two actual seismic waves. Based on the Rayleigh damping assumption, the damping ratio of two reference modes of Rayleigh damping is conservatively determined to be 0.5% based on both structural damping and aerodynamic damping. In addition, we compared the simplified model of single-mass oscillator which neglected the high-order vibration modes and the actual mass distribution of the tower recommended by relevant international codes and guidelines and the time-history analysis results of the mass model used in this paper. The results show that the seismic response of the wind turbine tower is significant. The contribution of the high-order vibration modes is related to the dynamic characteristics of the structure and the selection of seismic waves. The high-order vibration modes have little effect on the displacement of the wind turbine tower and the acceleration of the tower. The moment has a certain influence on the shear stress effect is more significant; time-history analysis, the single mass oscillator simplified model will be biased to unsafe seismic response results.