基于EMD和最小二乘法的基线飘移研究
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摘要
模拟和数字加速度仪记录的一个主要问题是参考基线的失真和飘移。在地震作用下的土-结构相互作用分析时,直接由地面加速度记录积分得到的位移通常存在基线飘移。在大跨度结构相互作用分析中,这种飘移会对分析结果带来严重的影响。提出一个简单的方法来移除长周期噪声进行基线调整。首先在时域内对加速度进行最小二乘拟合处理,接着通过EMD提取趋势项来进一步去除积分位移中的长周期影响。通过数值模拟信号和实测记录对比验证了此方法的可靠性。
A major problem encountered in analog or digital accelerograms is distortion and shift of the reference baseline.Accumulated experience indicates that direct integration of the ground acceleration data provided for seismic soil-structure interaction analysis often causes unrealistic drifts in the derived displacement,which may have a significant effect on large-scale interaction analysis.A simple approach was proposed to remove long-period noise for acquiring a realistic displacement-time series.In the approach,the acceleration data were baseline-corrected in the time domain using the least-square curve fitting technique,and then empirical mode decomposition (EMD) was used to extract signal trend to remove effect produced by long-period signal.Both simulated and field measured signals were employed to demonstrate the feasibility of the approach.
A major problem encountered in analog or digital accelerograms is distortion and shift of the reference baseline.Accumulated experience indicates that direct integration of the ground acceleration data provided for seismic soil-structure interaction analysis often causes unrealistic drifts in the derived displacement,which may have a significant effect on large-scale interaction analysis.A simple approach was proposed to remove long-period noise for acquiring a realistic displacement-time series.In the approach,the acceleration data were baseline-corrected in the time domain using the least-square curve fitting technique,and then empirical mode decomposition (EMD) was used to extract signal trend to remove effect produced by long-period signal.Both simulated and field measured signals were employed to demonstrate the feasibility of the approach.
引文
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[2]Boore D M.Effect of baseline corrections on response spectra for two recordings of the1999Chi-Chi,Taiwan,Earthquake[R].US Geological Survey,Open-file report99-545,Ver-sion1.0.
[3]Boore D M.Effect of baseline correction on displacement and response spectra for several recordings of the1999Chi-Chi,Taiwan,Earthquake[J].Bull Seism Soc Am,2001,91:1199-1211.
[4]Ivan W D,Moser M A,Peng C Y.Some observation on strong motion earthquake measurement using a digital acceler-ograph[J].Bssa,1985,75:1223-1246.
[5]周雍年,章文波,于海英.数字强震仪记录的长周期误差分析[J].地震工程与工程振动,1997,17(2):1-9.
[6]陈厚群.中国水工结构重要强震数据及分析[M].北京:地震出版社,2000.
[7]David Greene.Correcting Drifts in Numerical Integration U-sing Wavelets[R].http://flagpole.mit.edu/applets/nu-mint/numint-plugin-1.3.html,2001.
[8]王福明,等.应用数值计算方法[M].北京:科学出版社,1992.
[9]Huang N E,Shen Z,Long S R,et al.The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis[J].Proc.R.Soc.Lond.A,1998,454:903-995.
[10]陈隽,李杰.振动信号趋势项提取的几种方法及其比较[J].福州大学学报(自然科学版),2005,10(33):42-45.
[11]Boore D M,Julian J B.Processing of strong-motion accelerg-rams:needs,options and consequences[J].Soil Dynamics and Earthquake Engineering,2005(25):93-115.
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