高层钢框架预应力索支撑结构脉动风模拟AR模型参数分析

Analysis of Parameters of the AR Model for Simulation of Fluctuating Wind on High-rise Steel Frame with Prestressed Cable Support

以高层钢框架预应力索支撑结构为例,研究了应用AR模型进行脉动风模拟时,模型的2个关键参数——时间步长、时域点数的取值对模拟结果的影响.在讨论基于AR模型的脉动风模拟方法的基础上,利用有限元软件Sap2000建立结构模型,利用Matlab编制AR算法程序,分别选用不同的时间步长、时域点数对结构进行脉动风速时程分析,将生成的脉动风速功率谱曲线与目标谱进行对比,根据曲线吻合情况确定参数的合理取值范围.结果表明,时间步长的取值对AR模型模拟结果有较大影响,其最优值域为0.10～0.18 s,超出这一范围均会导致功率谱曲线与目标谱偏离,降低模拟精度；时域点数对AR模型模拟精度的影响较小,可根据工程需要选择时域点数.

Two critical parameters of the AR model are studied in the simulation of the fluctuating wind-time step and time points, focusing on the influence of the two parameters on the simulation of a high-rise steel frame with prestressed cable supports. The simulation of the fluctuating wind is based on the AR model, the finite element software Sap2000 is used to build the structural model, a mathematical software is used to program the AR model. Various values of the two parameters are selected, the modal analysis and the time history analysis of the structure are made. The ensemble power spectrum curve and the ensemble cross power spectrum curve are compared with the target power spectrum curve, and the reasonable value can be selected through the match of two curves. It is indicated that the value of the time step has a great effect on the accuracy of the simulation, and the suitable value should be around 0.10-0.18 s, if the value exceeds the range, the ensemble power spectrum can not match the target power spectrumand the accuracy of the simulation can not be ensured. The number of time points have little impact on the simulation.