Output-only damping estimation of structures using enhanced frequency domain decomposition method

Q: How can I download an article?

To download an article from SID, first log in to the site, search for the article title, and click on the 'Download Article' option.

Q: How can I download an ISI article?

To download an ISI article on SID, enter the keyword or article title in the search bar, view the relevant results, click on the desired article, and select the 'Download Article' option.

Q: How can I access the SID database?

To access the SID database, visit SID.ir, create an account, and log in to access scientific resources.

Q: Is downloading articles from SID free?

Some articles on SID are available for free, while others require payment. Details are specified on the article's page.

GHALISHOOYAN M.; SHOOSHTARI A.; Abdelghani m.

مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

Journal Paper

Paper Information

Journal: Modares Civil Engineering journal Year:2018 | Volume:18 | Issue:2 Page(s): 181-192

Download Full-Text

Persian Verion

View:

374

Download:

Cites:

Information Journal Paper

Title

Output-only damping estimation of structures using enhanced frequency domain decomposition method

Author(s)

GHALISHOOYAN M. | SHOOSHTARI A. | Abdelghani m. | Issue Writer Certificate

Keywords

Output-only modal damping estimationQ1

Enhanced frequency domain decomposition methodQ1

In-operation modal appropriation algorithmQ1

Abstract

Modal parameter identification of structures is of significant importance in many fields of civil and mechanical engineering. Output-only modal identification methods have gained great attention of civil engineers community in recent years. The algorithms estimating the dynamic parameters (natural frequencies, mode shape vectors and modal damping ratios) of structures just based on the output responses, became popular as operational modal analysis (OMA) or output-only modal analysis or ambient vibration analysis. In the context of OMA, the force acting on the structure should be stochastic, smooth and broadband and there is no need to measure it. Therefore, these methods are appropriate for identification of huge and complex civil structures. One of the most well-established and popular methods of OMA is frequency domain decomposition (FDD) proposed by Brincker et al. Estimation procedure of FDD is based on singular value decomposition of power spectral density matrix of structure responses. Then, the single degree of freedom spectral bell is obtained using modal assurance criteria (MAC) and transformed to correlation function of corresponded degree of freedom by inverse Fourier transform. Later, Brincker et al. presented the enhanced frequency domain decomposition (EFDD) method to estimate not only modal frequencies (with higher accuracy in the comparison with FDD) and mode shapes, but also modal damping ratios. Despite the high capability of EFDD in frequency and mode shape estimation, it still suffers from some limitations in identifying modal damping ratio. This paper first aims to investigate the modal parameters identification by EFDD and explains its merits and demerits and then proposes in-operation modal appropriation (INOPMA) algorithm for use with EFDD to improve the modal damping estimation. The key idea of INOPMA is to realize that the correlation sequence of the system output (subjected to random input) is the sum of decaying sinusoids with a certain phase shift and therefore it may be considered as an impulse response. The convolution of this correlation sequence with a pure sine wave allows the isolation of the mode at a characteristic frequency which depends on the modal damping ratio. By using a force in quadrature of phase with a sine wave, it is possible to estimate the damping ratio which in turn allows the estimation of the undamped natural frequency. In fact, modal damping ratios are first estimated by INOPMA and natural frequencies are then identified based on damping ratio values. By 70 times simulation of a four-story shear frame, capability of proposed method is validated for damping estimation through EFDD analysis. The results are then compared with the ones derived from the typical EFDD method. Regarding randomness of input force, different results are obtained by each new simulation run. So, the comparison process should be performed based on several numbers of simulations. The number of simulation was adopted in a way that the mean or variance of estimated modal damping ratios converges to a constant value. The relative error (the exact value minus the estimated value over the exact value) and variance of the set of the estimated modal dampings are regarded as comparison indexes. Finally, it is shown that by proposed method, the damping ratios are estimated with much less variance and error. Moreover, the ambient vibration test data of Z24 bridge was utilized as a benchmark application case in order to evaluate the capability of the proposed method for modal damping estimation and favorable results were obtained.

Cites

No record.

References

No record.

Cite

APA: Copy

GHALISHOOYAN, M., SHOOSHTARI, A., & Abdelghani, m.. (2018). Output-only damping estimation of structures using enhanced frequency domain decomposition method. MODARES CIVIL ENGINEERING JOURNAL, 18(2 ), 181-192. SID. https://sid.ir/paper/256781/en

Vancouver: Copy

GHALISHOOYAN M., SHOOSHTARI A., Abdelghani m.. Output-only damping estimation of structures using enhanced frequency domain decomposition method. MODARES CIVIL ENGINEERING JOURNAL[Internet]. 2018;18(2 ):181-192. Available from: https://sid.ir/paper/256781/en

IEEE: Copy

M. GHALISHOOYAN, A. SHOOSHTARI, and m. Abdelghani, “Output-only damping estimation of structures using enhanced frequency domain decomposition method,” MODARES CIVIL ENGINEERING JOURNAL, vol. 18, no. 2 , pp. 181–192, 2018, [Online]. Available: https://sid.ir/paper/256781/en

Related Journal Papers