基于香农采样定理的结构风振时域计算改进

基于同步测点的风压时程数据的响应计算有两种方法:时域法和频域法,它们得到的结果存在一定的差异。针对如何改善时域算法的精度进行研究,提出基于香农采样定理对风压时程数据进行加密的方法。将此方法运用到一个有解析解的两自由度结构算例和一个实际工程算例中,对采样数据量和采样频率都一定的荷载时程数据进行香农插值加密;分别采用插值加密之后的数据与未插值加密的数据进行计算,得到频域和时域结果。通过计算结果的比较得到以下结论:荷载时程数据相同的情况下,对于风致振动响应,频域计算的结果一般比时域计算更精确,时域计算的误差主要由高频部分的误差引起;运用香农采样定理,对已采得的数据进行插值加密,频域计算精度基本不变,但时域计算精度能得到提高。

Improvement of Wind-induced Vibration Analysis inTime Domain Based on Shannon Sampling Theorem

Based on the time history data of wind pressure obtained by synchronization pressure test in wind tunnel, there are two different methods to calculate the vibration response: time domain method and frequency domain method, from which the results obtained have some differences. To improve the accuracy of time domain method, a scheme to densify the time history data of wind pressure based on Shannon sampling theorem has been proposed in present paper. By applying this approach both to a two-degree-of-freedom system with theoretical solutions and to a practical project, the interpolated and densified data for each certain time history of load have been obtained. The responses are calculated by the processed data as well as the raw data to conduct time-domain and frequency-domain analyses. Through the comparison among those results, we come to the conclusions that: (i) For the calculation of wind-induced response, the frequency domain method can get more accurate results than the time domain method by a certain time history data of load, the differences of which come from the error of high frequency parts; (ii) By using the Shannon sampling theorem, the accuracy of the time domain method can be improved while the results obtained from frequency domain method are barely changed.