海上风机三桩基础与上部结构动力响应分析

Dynamic response analysis of tripod pile foundation and superstructure of offshore wind turbine

基于ANSYS有限元平台,建立了海上风机三桩基础与上部结构一体的三维模型;采用Block Lanzcos法进行模态分析,得到风机结构的各阶模态振型,确定了结构的振动特性;并结合模态分析结果,考虑周期性波浪荷载的作用,对结构模型进行了瞬态动力分析。结果表明:海上风机三桩基础与上部结构模态振型较容易表现为弯曲形式,结构的抗弯性能要求较高。在波浪荷载作用下各关键部位的位移与应力时程曲线随时间的变化规律都表现为周期性波动,但又存在差异。对于位移时程曲线,离基础越远的部位,其位移幅值越大,波动非线性特性也越明显;对于应力时程曲线,应力幅值主要位于立柱顶端,即立柱与塔筒连接部位。波浪荷载对结构的受力和变形影响较大,不容忽视。

A 3D numerical model for tripod pile foundation and superstructure of an offshore wind turbine was established based on ANSYS finite element platform. The modal shapes and vibration characteristics of the FEM were determined through the modal analysis by using Block Lanzcos method. Considering the effect of periodic wave loads,the dynamic response characteristics of the FEM were respectively calculated through the transient analysis.Therefore,the time-history curves of displacement and stress in the key parts of the structure were obtained. The analysis results show that： the tripod pile foundation and superstructure of the offshore wind turbine were easy to show as the bending form,indicating the higher bending performance of the structure. Under wave loading,the time-history curves of displacement and stress showed a periodic oscillatory motion with the change of time,but there were also differences. As to the time-history curves of displacement,the far the key parts away from the foundation,the larger the displacement amplitude,and the more remarkable the nonlinear characteristics of the curves. As to the time-history curves of stress,the stress amplitude appeared at the top of the column,which is the connecting part between the column and the tower. The wave loads cannot be ignored,which have important influences on the stress state and deformation of the offshore wind turbine structure.