Damage Detection Using Ultrasonic Techniques in Concrete-Filled Steel Tubes (CFSTs) Columns

Area of Science:

• Materials Science
• Structural Engineering
• Non-Destructive Testing

Background:

• Concrete-filled steel tubes (CFSTs) are vital structural components.
• Internal defects like air voids can compromise CFST integrity.
• These defects are often undetectable by visual inspection.

Purpose of the Study:

• To investigate the efficacy of ultrasound techniques for detecting internal air voids in CFSTs.
• To apply Broadband Ultrasound Attenuation (BUA) for void localization.
• To correlate ultrasound signal characteristics with defect percentages.

Main Methods:

• Ultrasound scanning of CFST samples with varying air void percentages using an immersion tank.
• Analysis of ultrasound signal amplitude, fundamental frequency, and Broadband Ultrasound Attenuation (BUA).
• Application of Fast Fourier Transform (FFT) and Short-Time Fourier Transform (STFT) for frequency domain analysis.

Main Results:

• A strong linear relationship was found between BUA averages and the percentage of air voids (r = 0.9873).
• Higher air void percentages correlated with increased BUA values.
• FFT and STFT analyses also demonstrated sensitivity to internal damage (r = -0.9799 and r = -0.9672, respectively).

Conclusions:

• The BUA technique is effective for locating and quantifying air voids in CFSTs.
• Ultrasound analysis, including BUA and frequency domain methods, significantly improves the detection of internal defects in CFSTs.
• These findings enhance the non-destructive evaluation capabilities for CFST structural health monitoring.