考虑初始倾斜的风机塔近场抗震可靠度分析

为研究初始倾斜对风机塔结构动力可靠度的影响，利用高精度免棱镜全站仪实测某2 MW风力发电塔缩尺模型的初始倾斜缺陷，并通过ABAQUS软件分别建立倾斜以及无倾斜的有限元模型，开展结构在八度多遇近场随机地震动作用下的动力反应分析，随之采用Kriging插值模型结合子集模拟方法，计算两类模型在首次超越破坏准则下的抗震可靠度。研究结果表明：初始倾斜缺陷放大了结构塔顶侧移响应，在均值意义上，初始倾斜缺陷使得该风机塔缩尺模型的塔顶侧移增幅达7.8%;当侧移阈值达到6 mm时，所述两类模型的可靠度均接近于1,当设计阈值超过此数值时，模型初始倾斜带来的不利影响可忽略不计，而当设计阈值不足时，结构安全水准会因初始倾斜的存在而明显降低。因此，在风机塔可靠性设计中，建议对初始倾斜缺陷带来的可靠度下降这一因素加以考虑。

Seismic reliability analysis of a wind turbine tower with initial tilt imperfection under near-field earthquake excitation

To study the effect of initial tilt on the dynamic reliability of a wind tower structure, the initial tilt defect of the scale model of a 2 MW wind turbine tower was measured using a high-precision reflectorless full station. Finite element models with and without tilt were established by using the ABAQUS software, and the analysis of stochastic dynamic responses of the models was conducted under the excitation of eight-degree frequent earthquakes. The seismic reliability of the two models based on the first excursion failure criterion was calculated using the Kriging model and the subset simulation method. Results show that the initial tilt defect amplifies the response of top drift for the wind turbine tower and causes the top drift of the scale model to increase by 7.8%. When the drift threshold reaches 6 mm, the reliability of the two models is close to 1; when the design threshold exceeds 6 mm, the adverse effect of the initial tilt can be ignored; when the design threshold is less than 6 mm, the safety level of the structure will be significantly reduced due to the initial tilt. As a result, the decrease in reliability caused by the initial tilt defect needs to be taken into consideration for the reliability design of wind turbine towers.