Fast Bayesian Ambient Modal Identification Incorporating Multiple Setups

• Published in: Journal of engineering mechanics Vol. 138; no. 7; pp. 800 - 815
• Main Authors: Au, S. K, Zhang, F. L
• Format: Journal Article
• Language: English
• Published: Reston, VA American Society of Civil Engineers 01-07-2012
• Subjects: Exact sciences and technology; Fundamental areas of phenomenology (including applications); Physics; Solid mechanics; Structural and continuum mechanics; Technical Papers; Vibration, mechanical wave, dynamic stability (aeroelasticity, vibration control...); Bayes estimation; Measurement; Vibration; Modal analysis; Probabilistic approach; Fast Fourier transformation; Iterative method; Vibration test; Spectral analysis; Operational modal analysis; Field tests; Fast algorithm; Bayesian analysis; Assembly
• ISSN: 0733-9399; 1943-7889
• DOI: 10.1061/(ASCE)EM.1943-7889.0000385

AbstractIn full-scale ambient vibration tests, many situations exist where it is required to obtain a detailed mode shape of a structure with a limited number of sensors. A common feasible strategy is to perform multiple setups with each one covering a different part of the structure while sharing some reference degrees of freedom (DOF) in common. Methods exist that assemble the mode shapes identified in individual setups to form a global one covering all measured DOF. This paper presents a fast Bayesian method for modal identification capable of incorporating the fast Fourier transform information in different setups consistent with probability logic. The method allows the global mode shape to be determined, taking into account the quality of data in different setups. A fast iterative algorithm is developed that allows practical implementation even for a large number of DOF. The method is illustrated with synthetic and field test data. Challenges of the mode shape assembly problem arising in field applications are investigated through a critical appraisal.