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| Unified theoretical model of Natural Excitation Technique (NExT) for multi-degree-of-freedom structural systems |
| Received:March 15, 2012 Revised:May 07, 2012 |
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| DOI：10.7511/jslx201303022 |
| KeyWord:natural excitation technique multi-input independent white noise displacement response cross-correlation function unified model |
| Author | Institution |
| 钟军军 |
清华大学土木工程系, 北京 |
| 董聪 |
清华大学土木工程系, 北京 |
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| Abstract: |
| Modal parameter identification (MPI) of structures subjected to highly uncertain natural excitations is crucial for structural health monitoring systems.The natural excitation technique (NExT) had provided a new approach for MPI of large complicated structures using operating ambient excitations.The original NExT proposed a theoretical model of MPI using the displacement cross-correlation function of structures subjected to single white noise excitation,but there was no proper theoretical model for the multi-input case.The analytical formula of the displacement cross-correlation function is derived for multi-degree-of-freedom structural systems subjected to multiple independent white noise excitations.A new function is defined using this cross-correlation function.It is proved that the new function is the sums of decaying sinusoids which have the same damped frequencies and damping ratios as the modes of the system.Consequently,it has the same form as impulse response function and thus can be used in standard MPI algorithms.Based on the new function,a unified theoretical model of NExT is proposed,which can extract structural modal parameters using displacement responses for the case of either single-input or multi-input. |