基于小波包变换的拟合非光滑目标谱的地震波生成(英文)

地震时程分析中需要使用符合规范的目标反应谱的地震记录,而以往的拟合目标谱的方法大多是针对目标谱为光滑曲线的情况的。在许多情况下,用单一的确定的反应谱,往往需要拟合不光滑的目标谱。给出一种基于小波包变换的、能够很好地拟合非光滑目标谱的地震时程调整方法。经过观察,发现地震记录经过小波包分解后的成分的频带中心频率与小波包成分的反应谱的峰值频率存在一定的偏差。基于这个现象给出了5个选择迭代点的策略,通过两个计算实例比较了这5个策略的效果。结果表明,以小波包成分的反应谱的峰值频率作为迭代点的策略能获得很好的拟合效果,并且在迭代过程中稳定趋向收敛,能很好地适用于不光滑目标谱的拟合。

Generation of artificial earthquakes for matching target response unsmooth spectrum via wavelet package transform

The seismic records of target response spectrum used in the time-history analysis should be allowed to meet the norms. However, the previous fitting methods of target spectrum are mostly for the situations that the target spectrum is a smooth curve. In many cases, it needs to match unsmooth target spectrum for single determined response spectrum. An adjustment of time history via wavelet packet transform was presented, which is able to fit unsmooth target spectrum. It was found that there is a certain bias between the band center frequency of the component of seismic record after wavelet packet decomposition and the peak frequency of response spectra of wavelet packet components. For this reason, five strategies were presented to select iteration points, and the effects of the five strategies were compared with two calculation examples. It was turned out that the peak frequency of the response spectrum of wavelet packet component can lead to good fitting effect when it is selected as the iteration point. In the iteration process, it shows great promise in fitting non-smooth target spectrum and has a trend of converge.