Synchrosqueezed wavelet transform for frequency and damping identification from noisy signals

Luis A. Montejo,Aidcer L. Vidot-Vega 국제구조공학회 2012 Smart Structures and Systems, An International Jou Vol.9 No.5

Identification of vibration parameters from the analysis of the dynamic response of a structure plays a key role in current health monitoring systems. This study evaluates the capabilities of the recently developed Synchrosqueezed Wavelet Transform (SWT) to extract instant frequencies and damping values from the simulated noise-contaminated response of a structure. Two approaches to estimate the modal damping ratio from the results of the SWT are presented. The results obtained are compared to other signal processing methods based on Continuous Wavelet (CWT) and Hilbert-Huang (HHT) transforms. It was found that the time-frequency representation obtained via SWT is sharped than the obtained using just the CWT and it allows a more robust extraction of the individual modal responses than using the HHT. However, the identification of damping ratios is more stable when the CWT coefficients are employed.

Synchrosqueezed wavelet transform for frequency and damping identification from noisy signals

Montejo, Luis A.,Vidot-Vega, Aidcer L. Techno-Press 2012 Smart Structures and Systems, An International Jou Vol.9 No.5

Identification of vibration parameters from the analysis of the dynamic response of a structure plays a key role in current health monitoring systems. This study evaluates the capabilities of the recently developed Synchrosqueezed Wavelet Transform (SWT) to extract instant frequencies and damping values from the simulated noise-contaminated response of a structure. Two approaches to estimate the modal damping ratio from the results of the SWT are presented. The results obtained are compared to other signal processing methods based on Continuous Wavelet (CWT) and Hilbert-Huang (HHT) transforms. It was found that the time-frequency representation obtained via SWT is sharped than the obtained using just the CWT and it allows a more robust extraction of the individual modal responses than using the HHT. However, the identification of damping ratios is more stable when the CWT coefficients are employed.

Applications of the wavelet transform in the generation and analysis of spectrum-compatible records

Suarez, Luis E.,Montejo, Luis A. Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.27 No.2

A wavelet-based procedure to generate artificial accelerograms compatible with a prescribed seismic design spectrum is described. A procedure to perform a baseline correction of the compatible accelerograms is also described. To examine how the frequency content of the modified records evolves with time, they are analyzed in the time and frequency using the wavelet transform. The changes in the strong motion duration and input energy spectrum are also investigated. An alternative way to match the design spectrum, termed the "two-band matching procedure", is proposed with the objective of preserving the non-stationary characteristics of the original record in the modified accelerogram.

Signal processing based damage detection in structures subjected to random excitations

Luis A. Montejo 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.6

Damage detection methodologies based on the direct examination of the nonlinear-nonstationary characteristics of the structure dynamic response may play an important role in online structural health monitoring applications. Different signal processing based damage detection methodologies have been proposed based on the uncovering of spikes in the high frequency component of the structural response obtained via Discrete Wavelet transforms, Hilbert-Huang transforms or high pass filtering. The performance of these approaches in systems subjected to different types of excitation is evaluated in this paper. It is found that in the case of random excitations, like earthquake accelerations, the effectiveness of such methodologies is limited. An alternative damage detection approach using the Continuous Wavelet Transform (CWT) is also evaluated to overcome this limitation. Using the CWT has the advantage that the central frequencies at which it operates can be defined by the user while the frequency bands of the detail functions obtained via DWT are predetermined by the sampling period of the signal.

Signal processing based damage detection in structures subjected to random excitations

Montejo, Luis A. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.6

Damage detection methodologies based on the direct examination of the nonlinear-nonstationary characteristics of the structure dynamic response may play an important role in online structural health monitoring applications. Different signal processing based damage detection methodologies have been proposed based on the uncovering of spikes in the high frequency component of the structural response obtained via Discrete Wavelet transforms, Hilbert-Huang transforms or high pass filtering. The performance of these approaches in systems subjected to different types of excitation is evaluated in this paper. It is found that in the case of random excitations, like earthquake accelerations, the effectiveness of such methodologies is limited. An alternative damage detection approach using the Continuous Wavelet Transform (CWT) is also evaluated to overcome this limitation. Using the CWT has the advantage that the central frequencies at which it operates can be defined by the user while the frequency bands of the detail functions obtained via DWT are predetermined by the sampling period of the signal.

Damping and frequency changes induced by increasing levels of inelastic seismic demand

Diego A. Aguirre,Luis A. Montejo 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.3

The objective in this research is to determine the feasibility of using changes on the dynamic properties of a reinforced concrete (RC) structure to identify different levels of seismic induced damage. Damping ratio and natural frequency changes in a RC bridge column are analyzed using different signal processing techniques like Hilbert Transforms, Random Decrement and Wavelet Transforms. The data used in the analysis was recorded during a full-scale RC bridge column shake table test. The structure was subjected to ten earthquake excitations that induced different levels of inelastic demand on the column. In addition, low-intensity white noises were applied to the column in-between earthquakes. The results obtained show that the use of the damping ratio and natural frequency of vibration as damage indicators is arguable.

On the use of numerical models for validation of high frequency based damage detection methodologies

Aguirre, Diego A.,Montejo, Luis A. Techno-Press 2015 Structural monitoring and maintenance Vol.2 No.4

This article identifies and addresses current limitations on the use of numerical models for validation and/or calibration of damage detection methodologies that are based on the analysis of the high frequency response of the structure to identify the occurrence of abrupt anomalies. Distributed-plasticity non-linear fiber-based models in combination with experimental data from a full-scale reinforced concrete column test are used to point out current modeling techniques limitations. It was found that the numerical model was capable of reproducing the global and local response of the structure at a wide range of inelastic demands, including the occurrences of rebar ruptures. However, when abrupt sudden damage occurs, like rebar fracture, a high frequency pulse is detected in the accelerations recorded in the structure that the numerical model is incapable of reproducing. Since the occurrence of such pulse is fundamental on the detection of damage, it is proposed to add this effect to the simulated response before it is used for validation purposes.

Damping and frequency changes induced by increasing levels of inelastic seismic demand

Aguirre, Diego A.,Montejo, Luis A. Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.3

The objective in this research is to determine the feasibility of using changes on the dynamic properties of a reinforced concrete (RC) structure to identify different levels of seismic induced damage. Damping ratio and natural frequency changes in a RC bridge column are analyzed using different signal processing techniques like Hilbert Transforms, Random Decrement and Wavelet Transforms. The data used in the analysis was recorded during a full-scale RC bridge column shake table test. The structure was subjected to ten earthquake excitations that induced different levels of inelastic demand on the column. In addition, low-intensity white noises were applied to the column in-between earthquakes. The results obtained show that the use of the damping ratio and natural frequency of vibration as damage indicators is arguable.

Unscented Kalman filter approach for tracking physical and dynamic properties of structures: Validation for multi-story buildings under seismic excitation

Gaviria, Carlos A.,Montejo, Luis A. Techno-Press 2021 Structural monitoring and maintenance Vol.8 No.2

An improved unscented Kalman filter approach is implemented to estimate induced displacements and changes in structural properties (stiffness, frequencies and damping) during the forced dynamic response of multistory buildings to seismic excitations. The methodology is validated using a fiber-based nonlinear model of a 4-story 4-bays reinforced concrete (RC) frame building subjected to a set of earthquakes causing different levels of inelastic demand on the structure. The variation of the dynamic properties is successfully estimated by iterative updating the filter parameters. The estimated peak values of stiffness and damping reached during the seismic excitation agree with peak inelastic demand values and seem appropriate for detection and damage diagnosis of RC structures.