不同频谱特性地震动下风电塔破坏分析

FAILURE ANALYSES OF A WIND TURBINE TOWER UNDER GROUND MOTIONS WITH DIFFERENT FREQUENCY CHARACTERISTICS

风力发电塔是一种顶部有较大质量的细长高耸结构,基本周期一般较长,因此可能会在不同频谱特性地震动下呈现不同的破坏模式。为了研究该问题,该文针对某典型风电塔,使用ABAQUS建立精细有限元模型,基于规范反应谱选择两类不同特征周期(0.4 s和1.1 s)的地震动记录,进行非线性动力时程分析。结果表明,对于0.4 s特征周期的地震动,地震动能量远离风电塔基本周期,结构受高阶振型影响较大,虽然初始塑性铰出现在底部,但全截面塑性铰和倒塌出现在中上部;对于1.1 s特征周期的地震动,地震动能量更加靠近风电塔基本周期,因此结构主要受第一振型控制,初始塑性铰、全截面塑性铰和倒塌出现在底部。对于同一条地震动,可能由于峰值加速度不同引起破坏位置变化。

Wind turbine tower is a slender high-rise structure with a heavy mass at the tower top. The fundamental period of the structure is generally long; therefore, it may present different failure modes under ground motions with different frequency characteristics. To investigate this issue, a detailed finite element model for a typical wind turbine tower was built in ABAQUS. Based on the response spectrum, two groups of ground motions were selected with two different design characteristic period（0.4 s and 1.1 s）. Non-linear time history analyses were performed, and structural failure modes were compared. For 0.4 s cases, since the frequency range for dominant ground motion energy is away from structural fundamental frequency, the tower responses contain more high mode contributions. The initial plastic hinge occurs at the bottom, but full-section plastic hinge and collapse location are at middle-upper part of the tower. For 1.1 s cases, the initial plastic hinge and the collapse section are both located at the tower bottom since structural responses are more affected by the first structural vibration mode. For the same ground motion record, the failure location may vary under different peak ground accelerations.