Identification of Modal Parameters with Unknown Input
The techniques developed for structural identification are typically devoted to obtain a structural model on the base of information on the response and on the forcing action. In many situations, however, it can be necessary to refer only to the measured responses. In this paper we describe the theoretical and computational aspects of a technique we have recently developed to identify the modal model in the frequency domain when the input is unknown. We show that this identification problem has an unique solution when at least three responses are known. Anyway, when one of the modal parameters is known, the other ones can be obtained on the base of two responses only. Numerical applications are carried out on plane framed structures ranging from three to eight stories. The modal model may also be incomplete, including only the lowest modes. The results obtained are satisfactory in most cases.
KeywordsModal Parameter Unknown Input Ambient Vibration Modal Model Experimental Modal Analysis
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- Capecchi D., De Angelis M. & Sepe V., 2002, Identification of structures subject to unknown seismic excitation, 3 rd Joint Conference GIMC and AACME, Giulianova (Italy), June 2002aGoogle Scholar
- Capecchi D., De Angelis M., Sepe V., Modal model identification with unknown nonstationary base motion, submitted to Meccanica, 2002bGoogle Scholar
- De Angelis M., Sepe V., Vestroni F., Identificazione dei parametri modali di una struttura eccitata alla base, Ingegneria Sismica, XVIII (3), pp. 42–50, 2001 (Abstract)Google Scholar
- Ewins D.J., Modal testing: theory and practice, Research Study Press — J. Wiley & Sons, 1986Google Scholar
- Katafygiotis L.S., Mickelborough N.C., Yuen K.V., Statistical identification of structural modal parameters using ambient response data, Proceed. 3rd Internation Conference on Computational Stochastic Mechanics, Island of Santorini, Greece, pp. 93–102, 1998Google Scholar
- Katafygiotis L.S., Yuen K.V., Statistical modal identification using ambient or string wind response data, Proceed. 4th Internation Conference on Stochastic Structural Dynamics, University of Notre Dame, Indiana (USA), pp. 387–394, 1998Google Scholar
- Luz E., Wallaschek J., Experimental modal analysis using ambient vibration, The International Journal of Analytical and Experimental Modal Analysis, vol. 7 (1), 1992, pp. 29–39Google Scholar
- Sepe V., De Angelis M, Capecchi D., Identificazione delle strutture sotto forzanti dinamiche non note, 10° Convegno Nazionale “L ‘ingegneria Sismica in Italia,Potenza-Matera 9–13 settembre 2001 (in Italian)Google Scholar