Damage Detection in CFST Column by Simulation of Ultrasonic Waves Using STFT-Based Spectrogram and Welch Power Spectral Density Estimate

Most damage detection methods have difficulty in detecting damage using only measurement data due to the existence of external noise. It is necessary to reduce the noise effect to obtain accurate information and to detect damage by the output-only measurement without baseline data at intact state and input data. This work imported the power spectral density estimation (PSE) of a signal to reduce the noise effect. By estimating the PSE to characterize the frequency content of the signal, this study proposes a damage detection method to trace the damage by the curvature of the PSE. Two numerical applications examine the applicability of the proposed method depending on a window function, frequency resolution, and the number of overlapping data in the PSE method. The knowledge obtained from the numerical applications leads to a series of experiments that substantiate the potential of the proposed method.

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Damage Detection of Shear Connectors Based on Power Spectral Density Transmissibility

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.569-570.1241 ◽

2013 ◽

Vol 569-570 ◽

pp. 1241-1248 ◽

Cited By ~ 4

Author(s):

Jun Li ◽

Hong Hao

Keyword(s):

Spectral Density ◽

Damage Detection ◽

Frequency Response ◽

Power Spectral Density ◽

Experimental Studies ◽

Measurement Data ◽

Response Functions ◽

Frequency Response Functions ◽

Shear Connectors ◽

Power Spectral

Damage of shear connectors in slab-on-girder structures will result in shear slippage between slab and girder, which significantly reduces the load-carrying capacity of the bridge. This paper proposes a dynamic damage detection approach to identify the damage of shear connectors in slab-on-girder bridges with power spectral density transmissibility (PSDT). PSDT formulates the relationship between the auto-spectral density functions of two responses. Measured impact force and acceleration responses from hammer tests are analyzed to obtain the frequency response functions at the slab and girder sensor locations by experimental modal analysis. When measurement data from the undamaged structure are available, PSDT from the slab response to the girder response is derived with the obtained frequency response functions. PSDT matrices in the undamaged and damaged states are directly compared to identify the damage of shear connectors. When the measurement data from the undamaged structure are not available, PSDT matrices from measured response at a reference sensor response to those of the slab and girder in the damaged state can also be used to detect the damage of shear connectors. Experimental studies with a concrete slab supported by two steel girders are conducted to investigate the accuracy and efficiency of the proposed approach. Identification results demonstrated that damage of shear connectors can be identified accurately and efficiently with and without measurement data from the undamaged structure.

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Research on Two-Step Damage Detection Method for Complex Gird Truss Structure under Wind Load

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.256-259.1131 ◽

2012 ◽

Vol 256-259 ◽

pp. 1131-1138

Author(s):

Hui Liu ◽

Xue Liang Wang ◽

Wei Lian Qu

Keyword(s):

Spectral Density ◽

Damage Detection ◽

Power Spectral Density ◽

Detection Method ◽

Damage Index ◽

Truss Structure ◽

Truss Structures ◽

Detection Methods ◽

Modal Strain Energy ◽

Power Spectral

Considering characteristics of gird truss structure, the suitable two-step damage detection method for these structures is proposed in the paper. The acceleration power spectral density sensibility of structural nodes is obtained by analyzing their acceleration power spectral density value caused every damaged structural bar. According to sensibility value, the range of influence of damaged structural bar is determined, then structural sub regions are divided and accelerators are distributed. The first step damage detection methods is identifying damaged bar occurrence region, it is extracting damage index to identify the damage occurrence region based on changes of acceleration response power spectral density of structure damaged after and before. The second step damage detection methods is located damaged bar in the region, it is completed by finding the damaged bar based on the theory of dissipation ratio of modal strain energy damage detection method. At last, taking the gird truss structure as numerical example, it shows the method has the capability to detect the damage of complex gird truss structures successfully.

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