Automatic modal identification of cable-supported bridges instrumented with a long-term monitoring system

Yiqing Ni, K. Q. Fan, G. Zheng, T. H.T. Chan, J. M. Ko

Research output: Journal article publicationConference articleAcademic researchpeer-review

15 Citations (Scopus)


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 to identify 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 deployed on the cable-stayed Ting Kau Bridge. With the continuously identified results, normal variability of modal vectors caused by varying environmental and operational conditions is observed. Such observation is very helpful for selection of appropriate measured modal vectors for structural health monitoring applications.
Original languageEnglish
Pages (from-to)329-339
Number of pages11
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 26 Nov 2003
EventSmart Structures and Materials 2003: Smart Systems and Nondestructive Evaluation for Civil Infrastructures - San Diego, CA, United States
Duration: 3 Mar 20036 Mar 2003


  • Automatic modal identification
  • Complex modal indication function
  • Environmental variability
  • Modal vector

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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