Browsing by Author "Chen, Liane Jye"

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Applying Time-Frequency Analysis on Earthquake Inputs and Structure Responses
(2014-01-01)
Huang, Chiung Shisnn
;
Su, Wei Chih
;
Chen, Liane Jye
;
Di Wang, Shing
;
土木工程學系
This work presents the use of a short time Fourier transform to identify the modal parameters (such as natural frequencies, damping ratios and mode shapes) of a structure from its earthquake responses data. The short time Fourier transform is applied to the measured acceleration responses of a structural system, and to reconstruct the autoregressive with exogenous input (ARX) model in time-frequency domain. The accuracy of this procedure is numerically confirmed; the effects of the remove frequency band and noise on the ability to accurately estimate the dynamic characteristics are also investigated.
Combining subspace approach and short time Fourier analysis for locating structural damage storeys
(2015-08-01)
Huang, Chiung Shiann
;
Chen, Liane Jye
;
Hung, Shih Lin
;
Ding, Chun Ting
;
Su, Wei Chih
This study proposes a novel and efficient approach for locating the floors of a building whose stiffnesses change after being subject to a strong earthquake. The floors that may be damaged are determined by comparing the unitary stiffness matrix in different stages in the life cycle of a building. To evaluate the coefficient matrices of a state-space model, the proposed procedure applies a subspace approach in conjunction with the short time Fourier analysis. The dynamic characteristics of a structure are determined from the coefficient matrices. Next, the unitary stiffness matrix is constructed by identifying natural frequencies and mode shapes. The effectiveness of the proposed procedure is verified using the measured earthquake acceleration responses of a three-storey structure that sustains damage on one or two floors and an eight-storey steel frame under a 200 Gal and a 1200 Gal earthquake, such as the Chi-chi earthquake that shook Taiwan on September 1999. The proposed scheme is compared to mode shape based approaches in identifying damaged floors, and is demonstrated to be superior to both MAC (Modal Assurance Criterion) and COMAC (Coordinate Modal Assurance Criterion).