基于小波能量传递函数谱的结构损伤识别
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摘要
为排除小波识别结构频率时地震动频带的干扰,提出了小波能量传递函数谱方法.该方法首先将地震动输入和结构地震反应小波谱分别沿时间轴积分,得到结构输入和输出的小波能量谱;然后将结构反应小波能量谱除以地震动输入小波能量谱,并定义为结构小波能量传递函数谱,该谱的脊线即为结构的时变频率.分别采用小波变换直接识别法和小波能量传递函数谱方法对一幢6层砌体结构在汶川地震一系列余震中的频率变化进行识别.结果表明,结构频率在较大的余震中明显降低,说明结构损伤有进一步发展.该方法可有效排除结构地震反应小波谱中地震动频带的干扰,准确识别结构在地震作用过程中的时变频率.
A new wavelet energy transfer function spectrum(WETFS)method was proposed in this study to remove frequency contamination of earthquakes from wavelet spectrum of structural responses in identifying fre-quency variation of structures.First,wavelet spectrums of earthquake excitation and structural response were integrated along time respectively to get wavelet energy spectrum of earthquakes and seismic responses.Then the WETFS was defined by dividing wavelet energy spectrum of earthquake excitation by that of structural re-sponse.The ridge on WETFS just represented the variation of structural frequencies.This method and the tra-ditional wavelet method were both applied on frequency identification of one 6-story masonry apartment build-ing.The seismic responses of this building during series of aftershocks of Wenchuan earthquake were measured and structural frequencies were identified to decrease remarkably during two aftershocks.The results of the two methods indicate that the WETFS method can identify variation of structural frequency accurately without con-tamination of earthquake excitation.
A new wavelet energy transfer function spectrum(WETFS)method was proposed in this study to remove frequency contamination of earthquakes from wavelet spectrum of structural responses in identifying fre-quency variation of structures.First,wavelet spectrums of earthquake excitation and structural response were integrated along time respectively to get wavelet energy spectrum of earthquakes and seismic responses.Then the WETFS was defined by dividing wavelet energy spectrum of earthquake excitation by that of structural re-sponse.The ridge on WETFS just represented the variation of structural frequencies.This method and the tra-ditional wavelet method were both applied on frequency identification of one 6-story masonry apartment build-ing.The seismic responses of this building during series of aftershocks of Wenchuan earthquake were measured and structural frequencies were identified to decrease remarkably during two aftershocks.The results of the two methods indicate that the WETFS method can identify variation of structural frequency accurately without con-tamination of earthquake excitation.
引文
[1]GURLEY K,KAREEM A.Applications of wavelet transform in earthquake,wind and ocean engineering[J].Engineering Structures,1999,21:149-167.
[2]KAREEM A,KIJEWSKI T.Time-frequency analysis of wind effects on structures[J].Journal of Wind Engi-neering and Industrial Aerodynamics,2002,90:1435-1452.
[3]KIJEWSKI T,KAREEM A.Wavelet transform for sys-tem identification in civil engineering[J].Computer-Aided Civil and Infrastructure Engineering,2003,18:339-355.
[4]YANG J N,LEI Y,LIN S,et al.Identification of natu-ral frequencies and damping of in site tall buildings u-sing ambient wind vibration data[J].Journal of Engi-neering Mechanics,2004,130(5):570-577.
[5]RUZZENE M,FASANA A,GARIBALDI L,et al.Nat-ural frequencys and dampings identification using wave-let transform:application to real data[J].Mechanical Systems and Signal Processing,1997,11(2):207-218.
[6]TCHAMITCHIAN P,TORRESANI B.Ridge and skele-ton extraction from the wavelet transform[C]//RUS-DAI M B.Wavelets and Their Applications[M].Bos-ton:Jones and Bartlett,1992:123-151.
[2]KAREEM A,KIJEWSKI T.Time-frequency analysis of wind effects on structures[J].Journal of Wind Engi-neering and Industrial Aerodynamics,2002,90:1435-1452.
[3]KIJEWSKI T,KAREEM A.Wavelet transform for sys-tem identification in civil engineering[J].Computer-Aided Civil and Infrastructure Engineering,2003,18:339-355.
[4]YANG J N,LEI Y,LIN S,et al.Identification of natu-ral frequencies and damping of in site tall buildings u-sing ambient wind vibration data[J].Journal of Engi-neering Mechanics,2004,130(5):570-577.
[5]RUZZENE M,FASANA A,GARIBALDI L,et al.Nat-ural frequencys and dampings identification using wave-let transform:application to real data[J].Mechanical Systems and Signal Processing,1997,11(2):207-218.
[6]TCHAMITCHIAN P,TORRESANI B.Ridge and skele-ton extraction from the wavelet transform[C]//RUS-DAI M B.Wavelets and Their Applications[M].Bos-ton:Jones and Bartlett,1992:123-151.
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