本文探討在非定常環境振動下利用結構系統響應進行模態參數識
別。以往亞伯拉罕時域法需基於自由衰減響應的限制下，方可識別出準確的模態參數，而本文提出利用延遲時間取樣擴充頻道法，直接利用非定常環境振動響應進行模態參數識別，可獲得良好之識別結果，並推廣至更廣泛的非定常環境振動響應。另外，引入模態置信因子來區分結構模態與非結構模態，最後利用數值模擬驗證本文所提出的理論。

Identification of modal parameters is considered from response data of structural systems under nonstationary ambient vibration. In this thesis, the ability of the Ibrahim time domain identification method has been studied to identify desired structural modal parameters, using a large identification model of nonstationary-response by employing the technique of channel-expansion. The use of the expanded model satisfies the need to determine the exact number of modes excited, but gives rise to the problem of distinguishing the structural modes from the non-structural modes. The modal confidence factor could then be used to effectively sort out structural modes from the identified modes. Numerical simulations confirm the validity of the proposed method for identification of structural modal parameters from nonstationary ambient response data.

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