SUMMARYPresent study aims to develop Hilbert-Huang transformation based signal processing scheme to identify the modal parameters of a reinforced concrete framed building subjected to multi-component earthquake excitations. An adaptive band-pass filtering strategy is developed to identify modal parameters (i.e. natural frequencies, damping and mode shapes). The proposed method is unique as it identifies the system parameters from the limited measurements due to arbitrary non-stationary excitations. The advantage of this technique is its ability to extract a complete set of modal frequencies from each measurement. The mode shapes are identified by updating the finite element model using the estimated modal parameters. In this context, the proposed method is effective as the large number of modal parameters identified from each measurement help to optimize the finite element model. The accuracy of the proposed method is demonstrated using both synthetic and actual measurements during an earthquake.

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An iterative Hilbert-Huang transformation (HHT) based algorithm is developed to extract the modal parameters of a linear time invariant (LTI) system excited by recorded non-stationary ground motion. The acceleration responses are measured using wireless sensors, which are filtered to avoid mode mixing prior to evaluate the instantaneous amplitude and phase using HHT. The band width is adjusted in successive iterations to achieve convergence in modal parameter estimation. The numerical study presented in this work discusses the efficiency of the identification strategy in the light of noise contaminated earthquake responses.