Adaptive HHT (AHHT) based modal parameter estimation from limited measurements of an RC-framed building under multi-component earthquake excitations

Abstract

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.

Identification of shear buildings using an instrumental variable method and linear integral filters

“…The cut-off frequency of this filter is set to 25 Hz since the predominant frequency content of the earthquakes lies between 1 and 20 Hz [38]. Note that the auxiliary model (39) has the same structure that the building model (4). The samples of € x à are used to build a matrix € u à , which has the same structure as € u in (12).…”

“…Moreover, this procedure permits eliminating the offset in the signal € x gmf at time t ¼ 5δ s (see Proposition 1 in Appendix B). Note that the correlation between ηðtÞ and μðtÞ is greatly reduced since ηðtÞ depends on acceleration measurements provided by the auxiliary model (39), which corresponds to acceleration estimates of the noise-free model (4). The parameter estimates produced by the off-line IV method are obtained by solving [37] Θ IV N ¼…”

Operational modal identification of structures based on improved empirical wavelet transform

“…These IMFs represent natural oscillatory modes embedded in the signal and behave as basic functions, which are derived from the signal itself. EMD has been widely applied for modal identification and structural damage identification . To improve the performance of using EMD for response decomposition against the noise effect in measured responses, Ensemble Empirical Mode Decomposition has been proposed .…”

“…EMD has been widely applied for modal identification and structural damage identification. [23][24][25][26] To improve the performance of using EMD for response decomposition against the noise effect in measured responses, Ensemble Empirical Mode Decomposition has been proposed. 27 However, the problem of mode mixing still exists.…”

Application of Hilbert Huang transform to identify the natural frequencies of steel frame

“…There are a lot of theoretical and practical studies that have been developed to this method for a wide variety of structures such as bridges, high buildings, offshore drilling platforms ... [4][5][6]. Mahato et al [7] applied HHT to identify the modal parameters of a reinforced concrete framed building and Kunwar et al [8] and Reddy et al [9] proposed the damage detection for bridge structure using the HHT technique.…”