Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Acoustic tomography for qualitative nondestructive evaluation (QNDE) of structural concrete using a new ultrasonic scanner source
In order to study the application of tomography for nondestructive imaging of flaws in concrete, four concrete walls were constructed with honeycombs, simulated voids, simulated cracks, poor quality concrete and steel rebar. A total of 11 tomographic images were obtained (each utilizing over 1700 data traces) using the rolling Ultrasonic Pulse Velocity (UPV) scanner source and a 150 kHz James Instruments UPV receiver. The source was excited at its 35 kHz resonant frequency, and the recorded signal was amplified and band-pass filtered between 20-40 kHz. The analog signal was digitized using a PC-based digital oscilloscope system at a 1 microsecond sampling interval. An example of a picked first arrival travel time and amplitude plot and a summary of the findings are shown. The travel time velocity tomography was most successful in locating voids in concrete (the voids also had the highest velocity contrast anomaly). Conventional Ultrasonic Pulse Velocity (UPV) tests also showed up to a 10 % delay in travel time for void versus sound concrete. Velocity tomography was also effective in identifying the location of the corehole in the Colorado School of Mines (CSM) wall. Evaluation of other defects included honeycombs, simulated open cracks and simulated microcracks. These comparatively small simulated defects indicated velocity reductions of less than or equal to 5 % versus sound concrete.
Acoustic tomography for qualitative nondestructive evaluation (QNDE) of structural concrete using a new ultrasonic scanner source
In order to study the application of tomography for nondestructive imaging of flaws in concrete, four concrete walls were constructed with honeycombs, simulated voids, simulated cracks, poor quality concrete and steel rebar. A total of 11 tomographic images were obtained (each utilizing over 1700 data traces) using the rolling Ultrasonic Pulse Velocity (UPV) scanner source and a 150 kHz James Instruments UPV receiver. The source was excited at its 35 kHz resonant frequency, and the recorded signal was amplified and band-pass filtered between 20-40 kHz. The analog signal was digitized using a PC-based digital oscilloscope system at a 1 microsecond sampling interval. An example of a picked first arrival travel time and amplitude plot and a summary of the findings are shown. The travel time velocity tomography was most successful in locating voids in concrete (the voids also had the highest velocity contrast anomaly). Conventional Ultrasonic Pulse Velocity (UPV) tests also showed up to a 10 % delay in travel time for void versus sound concrete. Velocity tomography was also effective in identifying the location of the corehole in the Colorado School of Mines (CSM) wall. Evaluation of other defects included honeycombs, simulated open cracks and simulated microcracks. These comparatively small simulated defects indicated velocity reductions of less than or equal to 5 % versus sound concrete.
Acoustic tomography for qualitative nondestructive evaluation (QNDE) of structural concrete using a new ultrasonic scanner source
Akustische Tomographie für die qualitative zerstörungsfreie Untersuchung von Baubeton mittels einer neuen Ultraschall-Abtastquelle
Jalinoos, F. (Autor:in) / Olson, L.D. (Autor:in) / Aouad, M.F. (Autor:in) / Balch, A.H. (Autor:in)
1995
8 Seiten, 2 Bilder, 1 Tabelle, 6 Quellen
Aufsatz (Konferenz)
Englisch
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