Autoregressive spectrum-guided variational mode decomposition for time-varying modal identification under nonstationary conditions

Time-varying parameter identification is essential for structural health monitoring and performance evaluation. In this paper, a combined method based on the variational mode decomposition and generalized Morse wavelet is proposed to identify the structural time-varying parameters. Based on the sparse property of structural response signals in wavelet domain, a fast iterative shrinkage-thresholding algorithm is adopted to reduce the noise. Then the de-noised signal is decomposed into multi- modes by the variational mode decomposition, and the generalized Morse wavelet is performed to identify the instantaneous frequency. To validate the proposed method, a numerical example including different frequency variations is studied. Experimental validations of a moving vehicle across a bridge and a time-varying cable system considering two patterns of cable tension variations in the laboratory are carried out to investigate the capability of the proposed approach. It is confirmed that the proposed approach can effectively perform the signal decomposition, while identifying the instantaneous frequencies of the time-varying systems accurately.

Download Full-text

Time-varying system identification using variational mode decomposition

Structural Control and Health Monitoring ◽

10.1002/stc.2175 ◽

2018 ◽

Vol 25 (6) ◽

pp. e2175 ◽

Cited By ~ 19

Author(s):

Pinghe Ni ◽

Jun Li ◽

Hong Hao ◽

Yong Xia ◽

Xiangyu Wang ◽

...

Keyword(s):

System Identification ◽

Time Varying ◽

Variational Mode Decomposition ◽

Mode Decomposition

Download Full-text

Modal Identification from Non-Stationary Responses of High-Rise Buildings by Variational Mode Decomposition and Direct Interpolation Techniques

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455420501151 ◽

2020 ◽

Vol 20 (11) ◽

pp. 2050115

Author(s):

Meng-Meng Sun ◽

Qiu-Sheng Li ◽

Kang Zhou ◽

Ying-Hou He ◽

Lun-Hai Zhi

Keyword(s):

Field Measurements ◽

Modal Identification ◽

Frame Structure ◽

The Novel ◽

Variational Mode Decomposition ◽

High Rise ◽

Mode Decomposition ◽

Structural Responses ◽

Novel Method ◽

High Level

For high-rise buildings subjected to ambient excitations such as typhoons and earthquake actions, their structural responses may include non-stationary features. Under such conditions, traditional modal identification methods may not be applicable due to the violation of the stationary assumption of the response signals. To deal with this issue, a novel modal identification method is presented in this paper based on combination of the variational mode decomposition (VMD) and direct interpolation (DI) techniques. Through numerical simulation study of a three-story frame structure, the effectiveness and accuracy of the combined VMD-DI method for modal identification of the structure are validated for the case of the structural responses containing non-stationary properties and high-level noise. Moreover, the novel method is further applied to the field measurements of acceleration responses of a 600[Formula: see text]m high skyscraper during a typhoon. The identified results verify the applicability and accuracy of the combined VMD-DI method in field measurements. This paper aims to provide an effective tool for modal identification from non-stationary structural responses of high-rise buildings.

Download Full-text

Output-only modal identification based on the variational mode decomposition (VMD) framework

Journal of Sound and Vibration ◽

10.1016/j.jsv.2021.116668 ◽

2021 ◽

pp. 116668

Author(s):

Shuaishuai Liu ◽

Rui Zhao ◽

Kaiping Yu ◽

Bowen Zheng ◽

Baopeng Liao

Keyword(s):

Modal Identification ◽

Variational Mode Decomposition ◽

Mode Decomposition ◽

Output Only

Download Full-text

Modal Identification Based on Hilbert Transform for Time-Varying System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.226-228.303 ◽

2012 ◽

Vol 226-228 ◽

pp. 303-307

Author(s):

Min Zheng ◽

Fan Shen

Keyword(s):

Hilbert Transform ◽

Modal Identification ◽

Time Varying ◽

Identification Methods ◽

Response Data ◽

Modal Response ◽

Mode Decomposition ◽

Time Histories ◽

The Hilbert Transform ◽

Instantaneous Frequencies

Modal identification methods based on the Hilbert Transform are applied to identify modal parameters of time-varying system using impulse response time histories. First, the response data are decomposed into modal responses through the empirical mode decomposition (EMD). Then, the Hilbert transform is applied to each modal response to obtain the instantaneous frequencies. The applications of the proposed methods are illustrated using a 3 degree-of-freedom (DOF) systems with time-varying dynamic characteristics. Numerical simulation results demonstrate that the proposed system identification methods yield good results.

Download Full-text

Variational Mode Decomposition Based Time-Varying Force Identification of Stay Cables

Applied Sciences ◽

10.3390/app11031254 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1254

Author(s):

Shitong Hou ◽

Bin Dong ◽

Jianhua Fan ◽

Gang Wu ◽

Haochen Wang ◽

...

Keyword(s):

Good Effect ◽

Time Varying ◽

Variational Mode Decomposition ◽

Stay Cable ◽

Cable Tension ◽

Force Identification ◽

Stay Cables ◽

Mode Decomposition ◽

Cable Force ◽

Cable Stayed Bridges

Stay cables are important structural members of cable-stayed bridges, which play a significant role in the health monitoring and assessment of cable-stayed bridges. The in-service cable force, which varies from the effects of vehicle load, wind load and other environmental factors, may cause fatigue damage in stay cables. Traditional force identification methods can only calculate the time-average cable force instead of the instantaneous force. A novel method has been proposed in this paper for identifying time-varying cable tension based on the variational mode decomposition (VMD) method. This recent method decomposes signals and adaptively estimates instantaneous frequency combined with the Hilbert–Huang transform method. In the proposed study, the time-varying modal frequencies were identified from stay cable acceleration data, and then the time-varying cable tension was identified by the relationship between cable tension and identified fundamental frequency. Scaled and full-scale models of stay cables were implemented successively to illustrate the validity of the proposed method. The results showed that the variational mode decomposition (VMD) method has a good effect on identifying the time-varying cable forces, even the sudden changes in cable force. According to the cable force identification results, the maximum error was 8.4%, which meets the actual application of time-varying cable force measurements. An on-site test was also implemented to monitor the cable force during a construction period, and the results showed that the proposed method can provide accurate real-time results for evaluation and decision-making.

Download Full-text