地震波时频特征及与结构地震响应的关系
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摘要
首先推导了离散S变换的基本算法,定义了反映地震波时频特性的时变幅值谱和时变能量谱;基于S变换提出了把原始波调整成具有目标反应谱的新方法,分析了El_centro波、Northridge波、Kobe波和人工合成波以及经调整后的各地震波的时频特征;对地震波的时变谱进行特征提取,提出了能反映地震波在时频空间中能量集中程度的新概念,即地震波的时频特征谱;通过分析发现,具有相似功率谱密度函数(即具有相似频域特征)的地震波,它们的弹性加速度反应谱可能有很大的差异,而具有相似时频特征谱的地震波,具有相似的弹性加速度反应谱;相关性分析表明地震波的时频特征谱与线性结构的弹性加速度反应谱具有很好的线性相关性;最后建立了地震波的时频特征谱与弹性加速度反应谱之间的近似转换关系式,此转换关系可作为合成具有目标反应谱的人工地震波使用。
The formulas of discrete S-transform are derived,and the time-varying amplitude spectrum and time varying energy spectrum based on S-transform are given.A new procedure is presented to generate an accelerograms whose elastic response spectrum is compatible with a target spectrum by using actual earthquake records as parents.The time-frequency characteristics of Northridge wave,El-centro wave,Kobe wave and an artificial wave are analyzed through numerical example.The time-frequency characteristic spectrum which reflects the centralized degree of energy of earthquake ground motion is extracted from the time varying energy spectrum.It is showed that the time-frequency characteristic spectrum is related linearly to the elastic acceleration response spectrum.Finally,the approximate transformation equation between the time-frequency characteristic spectrum and the elastic acceleration response spectrum is established.
The formulas of discrete S-transform are derived,and the time-varying amplitude spectrum and time varying energy spectrum based on S-transform are given.A new procedure is presented to generate an accelerograms whose elastic response spectrum is compatible with a target spectrum by using actual earthquake records as parents.The time-frequency characteristics of Northridge wave,El-centro wave,Kobe wave and an artificial wave are analyzed through numerical example.The time-frequency characteristic spectrum which reflects the centralized degree of energy of earthquake ground motion is extracted from the time varying energy spectrum.It is showed that the time-frequency characteristic spectrum is related linearly to the elastic acceleration response spectrum.Finally,the approximate transformation equation between the time-frequency characteristic spectrum and the elastic acceleration response spectrum is established.
引文
[1]陈健云,李静,周晶,林皋.地震动时频谱对小拱坝非线性响应的影响[J].振动工程学报,2003,16(2):207―211.Chen Jianyun,Li Jing,Zhou Jing,Lin Gao.Effects of time-frequency joint non-stationariness on the response of arch dam[J].Journal of Vibration Engineering,2003,16(2):207―211.(in Chinese)
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[6]曹晖,赖明,白绍良.地震地面运动的局部谱密度描述及其估计方法[J].世界地震工程,2004,20(2):43―49.Cao Hui,Lai Ming,Bai Shaoliang.The description of earthquake ground motion based on local spectral density and its estimation methods[J].World Information on Earthquake Engineering,2004,20(2):43―49.(in Chinese)
[7]樊剑,刘铁,胡亮.基于现代时频分析技术的地震波时变谱估计[J].振动与冲击,2007,26(11):79―82.Fan Jian,Liu Tie,Hu Liang.Time-varying spectrum estimation of earthquake ground motion via modern time-frequency analysis[J].Journal of Vibration and Shock,2007,26(11):79―82.(in Chinese)
[8]樊剑,吕超,张辉.基于S变换的地震波时频分析及人工调整[J].振动工程学报,2008,21(4):381―386.Fan Jian,Lu Chao,Zhang Hui.Time-frequency analysis and artificial modify of earthquake records based on S transform[J].Journal of Vibration Engineer,2008,21(4):381―386.(in Chinese)
[9]Stockwell R G.A basis for efficient representation of the S-transform[J].Digital Signal Processing,2007,17(3):371―393.
[10]Pinnegar C R.Time-frequency and time-time filtering with the S-transform and TT-transform[J].Digital Signal Processing,2005,15(5):604―620.
[2]Wang Junjie;Fan Lichu,Qian Shie,Zhou Jing.Simulations of non-stationary frequency content and its importance to seismic assessment of structures[J].Earthquake Engineering and Structural Dynamics,2002,31(10):993―1005.
[3]Spanos P D,Jale Tezcan,Petros Tratskas.Stochastic processes evolutionary spectrum estimation via harmonic wavelets[J].Computer Methods and Application Mechanics Engineering,2005,194(12):1367―1383.
[4]Spanosa P D,Giaralisb A,Politis N P.Time-frequency representation of earthquake accelerograms and inelastic structural response records using the adaptive chirplet decomposition and empirical mode decomposition[J].Soil Dynamics and Earthquake Engineering,2007,27(6):675―689.
[5]Wen Y K,Gu Ping.Description and simulation of non-stationary processes based on Hilbert spectra[J].Journal of Engineering Mechanics,2004,130(9):942―951.
[6]曹晖,赖明,白绍良.地震地面运动的局部谱密度描述及其估计方法[J].世界地震工程,2004,20(2):43―49.Cao Hui,Lai Ming,Bai Shaoliang.The description of earthquake ground motion based on local spectral density and its estimation methods[J].World Information on Earthquake Engineering,2004,20(2):43―49.(in Chinese)
[7]樊剑,刘铁,胡亮.基于现代时频分析技术的地震波时变谱估计[J].振动与冲击,2007,26(11):79―82.Fan Jian,Liu Tie,Hu Liang.Time-varying spectrum estimation of earthquake ground motion via modern time-frequency analysis[J].Journal of Vibration and Shock,2007,26(11):79―82.(in Chinese)
[8]樊剑,吕超,张辉.基于S变换的地震波时频分析及人工调整[J].振动工程学报,2008,21(4):381―386.Fan Jian,Lu Chao,Zhang Hui.Time-frequency analysis and artificial modify of earthquake records based on S transform[J].Journal of Vibration Engineer,2008,21(4):381―386.(in Chinese)
[9]Stockwell R G.A basis for efficient representation of the S-transform[J].Digital Signal Processing,2007,17(3):371―393.
[10]Pinnegar C R.Time-frequency and time-time filtering with the S-transform and TT-transform[J].Digital Signal Processing,2005,15(5):604―620.
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