空间结构三维风时程模拟及其小波分析

基于谐波叠加法和快速傅里叶变换提出改进方法,用于大跨空间结构的三维相关风速时程模拟。风速功率谱被分解为频率谱函数和相干函数;研究表明在空间三个方向上模拟风速功率谱皆收敛于目标风谱。小波分析在时域和频域上同时具有良好局部化特性。使用小波技术对模拟的风速时程进行时频分析,利用离散小波变换分解和重构风速时程,用小波系数描述风速信号特性。采用最大熵值法减少风速时程分析在时频域上的信息损失并提高效率。计算显示,改进方法速度快、精度高,弥补了传统手段模拟空间结构三维风速时程耗时冗长、精度低的缺陷,小波分析在风速时程分析中具有理想的可靠性和保真性。

THE IMPROVED SIMULATION AND WAVELET ANALYSIS OF WIND VELOCITY TIME SERIES FOR LONG-SPAN SPATIAL STRUCTURES

Based on the wave superposition technique and fast Fourier transformation (FFT), an improved method is presented to simulate three-dimensional relevant wind velocity time series for a mass of nodes of long span spatial structure. The wind Power Spectral Density (PSD) is divided into frequency spectral function and coherency function. The simulated spectrum converges upon the given target spectrum in all three directions. The time-frequency characteristics of the simulated wind velocity time series for long span spatial structure is studied by means of wavelet analysis technique, which possesses excellent localized characteristics in both time domain and frequency domain and is capable of focusing on any details of the objective signal series. The discrete wavelet transformation is introduced to decompose and reconstruct the discrete wind velocity time series. The maximum entropy method is adopted to reduce the information loss and improve computational efficiency. Results show that the present method has better accuracy and higher efficiency than traditional technique in the simulation of wind velocity time series. The reliability of the wavelet technique for the analysis of wind velocity time series is also proved through numerical examples.