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Structural Engineering and Mechanics Volume 19, Number 2, January30 2005 , pages 123-139 DOI: https://doi.org/10.12989/sem.2005.19.2.123 |
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Automatic modal identification and variability in measured modal vectors of a cable-stayed bridge |
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Y. Q. Ni, K. Q. Fan, G. Zheng and J. M. Ko
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| Abstract | ||
| An automatic modal identification program is developed for continuous extraction of modal parameters of three cable-supported bridges in Hong Kong which are instrumented with a long-term monitoring system. The program employs the Complex Modal Indication Function (CMIF) algorithm for identifying modal properties from continuous ambient vibration measurements in an on-line manner. By using the LabVIEW graphical programming language, the software realizes the algorithm in Virtual Instrument (VI) style. The applicability and implementation issues of the developed software are demonstrated by using one-year measurement data acquired from 67 channels of accelerometers permanently installed on the cable-stayed Ting Kau Bridge. With the continuously identified results, variability in modal vectors due to varying environmental conditions and measurement errors is observed. Such an observation is very helpful for selection of appropriate measured modal vectors for structural health monitoring use. | ||
| Key Words | ||
| cable-stayed bridge; monitoring system; automatic modal identification; complex modal indication function; modal vector; modal variability. | ||
| Address | ||
| Y. Q. Ni Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong K. Q. Fan School of Information, Wuyi University, Jiangmen, Guangdong 529020, P. R. China G. Zheng Chongqing Communications Research and Design Institute, Chongqing 400067, P. R. China J. M. Ko Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong | ||