【作者】 何颖；

【导师】 梁建文；

【作者基本信息】 天津大学 ， 防灾减灾与防护工程， 2006， 硕士

【摘要】 本文对目标谱符合给定反应谱的地震动模拟方法进行了研究,从真实地震动特征出发,基于Hilbert-Huang变换(HHT)提出了一种新的非平稳地震动过程模拟方法。通过与国内外本领域研究情况的比较,本文的研究工作能够更精确地模拟实际地震动的非平稳特征。首先回顾了具有统一统计特征的非平稳地震动过程模拟的研究状况,阐明了传统方法仅考虑了场地地震动幅值的非平稳性的不足之处。接着引用了一种模拟产生目标谱符合给定功率谱的新方法,该方法产生的模拟样本过程在幅值上和频率上均是非平稳的,幅值和频率的非平稳取决于目标时变功率谱。这是作者进行研究的理论基础之一。随后对Hilbert-Huang变换作了简要介绍,并与傅立叶变换和小波变换进行比较。HHT方法由经验模态分解(EMD)与经典的Hilbert变换结合而成。由HHT方法得到的Hilbert功率谱能清晰地显示随时间变化的频率特征,因而能更精确的表达地震动时程频域内非平稳的特性。本文在此基础上进行研究拓展,详细推导阐述了一种模拟非平稳地震动过程的有效方法。该方法以幅值谱修正方法为基础,结合HHT变换,引入Hilbert谱,保留了原始地震记录在幅值和频率上的非平稳特性。最后,论文以El Centro地震波的Hilbert功率谱为出发点,给定目标谱为第一类场地反应谱,对此方法进行了验证。验证结果表明,本文方法能够精确的反映实际地震动频率幅值的非平稳特征,值得进一步的研究应用。更多还原

【Abstract】 Simulation methods for generating earthquake with target spectra compatible with prescribed response spectra are investigated in this paper. To get more realistic results, a new method is proposed based on Hilbert-Huang transform(HHT).Compared to present research situation, the research work in this paper supplies a comparatively accurate method for the simulation of non-stationary ground motion processes. Firstly, after a quick review of the research on non-stational ground motion with equivalent Stochastic characteristics, the weaknesses of traditional methods which are able to consider the non-stationarity of ground motion amplitudes only are illustrated. This new simulation method is introduced in this paper next. According to it,those simulated sample processes reflect the earthquake ground Motion’s non-stationary both in amplitude and frequency content related closely to the time-dependent object Power spectra which is one theory basis for the research work herein. The HHT method is also summarized briefly in this paper and compared with Fourier transform and wavelet analysis. The HHT method is developed through integrating empirical mode decomposition (EMD) and classical Hilbert transform. The Hilbert spectra resulted from HHT can provide more significant description of time-varying frequency composition and thus represent the non-stationarity of earthquake ground motion more accurately. On basis of the theory discussed above, an effective method for simulation of non-stationary ground motion processes is illustrated in more detail subsequently. This innovative method, based on the technique of amplitudes correction, integrating with the HHT method and introducing the Hilbert spectra, enables it possible to maintain the non-stationarity both in amplitudes and frequency content of the original earthquake record. Finally, with El Centro strong ground motion recording being the original recording and response spectra of first kind ground the target spectra, the accuracy of this proposed method is verified.The conclution reached is that it is able to represent the non-stationarity of earthquake ground motion more veritably and thus更多还原