Ultrasound based Crack Depth Estimation in Steel-fiber Reinforced Concrete

Öz

Estimation of the depth of surface-breaking cracks caused by bending in concrete has crucial importance in order to predict the remaining load capacity of a structural member. In practice, ultrasonic tests are the most commonly used non-destructive methods to assess the condition of concrete. However, the commercial ultrasound-based methods focus on the estimation of thickness of the structural element rather than the crack depth. The cracks cause dispersion and attenuation in the propagating waves, and thus by monitoring the changes in these wave characteristics, diagnostic indexes correlated with the crack depth can be defined. This paper explains this approach through the tests performed on seven laboratory-scale steel-fiber reinforced concrete beams (50x10x10 cm3). The beams are loaded under the crack-controlled three-point bending test until a specific crack depth is reached. These beams are then subjected to ultrasonic testing to acquire the propagating surface waves. The recorded signals are analysed by utilizing signal processing techniques, including discrete wavelet transform and frequency-wavenumber analysis in order to extract two diagnostic features, namely, material attenuation coefficient and dispersion index. It is shown that both diagnostic features are able to detect the crack and estimate its depth.

Anahtar Kelimeler

• Non-destructive testing
• crack depth estimation
• steel-fiber reinforced concrete
• ultrasonic waves
• dispersion
• attenuation

Ultrasonik Yöntemler ile Çelik-lif Takviyeli Betonda Eğilme Çatlaklarının Derinlik Tayini

Öz

Betonda eğilme çatlaklarının derinliklerin tespit edilmesi, yapısal elemanların kalan yük taşıma kapasitelerinin tayini için önem taşımakladır. Uygulamada, mevcut tahribatsız ultrasonik test yöntemleri çatlak derinliğinin tespitinden ziyade ya elemanların kalınlıklarının ölçülmesinde ya da mukavemet tayininde kullanılmaktadır. Bir cisim içinde yayılmakta olan ultrasonik dalgalar bir çatlak ile karşılaştıkları zaman dalga karakteristiklerinde değişim gözlemlenir. Bu değişimin takibi ve ölçümü ile çatlak derinliğinin tayini mümkündür. Bu makale, bu yaklaşıma dayanarak geliştirilen tanı metodunu, 7 adet çelik-lifli beton kiriş numune (50x10x10 cm3) üzerinde gerçekleştirilmiş olan ultrasonik testler üzerinden incelemektedir. Kiriş numeneler çatlak-kontrollü üç-noktalı-eğilme testi ile belli bir çatlak derinliğine ulaşılana kadar hasara uğratılmış ve akabinde gerçekleştirilen ultrasonik testler ile dalga yayılımı kaydedilmiştir. Kaydedilen dalga sinyal serileri, ayrık wavelet dönüşüm ve frekans-dalganumarası analizi gibi dijital sinyal işleme teknikleri ile analiz edilerek iki tip tanı indeksi elde edilmiştir. İlk tanı indeksi malzeme sönüm katsayısı α, dalga sönümünü; diğer tanı indeksi ‘dağılım indeksi DI’ ise, dalgaların faz hızındaki dağılımı temsil etmektedir. Her iki tanı indeksinin de çatlak tespiti ve derinlik tahmininde faydalı oldukları görülmüştür.

Anahtar Kelimeler

• tahribatsız muayene
• çatlak derinlik ölçümü
• çelik-lif takviyeli beton
• ultrasonik yüzey dalgaları
• dalga sönümü
• dalga dağılımı

Kaynakça

1. ASTM C597-16. (2016) Standard Test Method for Pulse Velocity Through Concrete. ASTM International, West Conshohocken, PA.
2. ACI 228.2R-13. (2013) Report on Nondestructive Test Methods for Evaluation of Concrete in Structure‪s. ACI Committee 228‬‬‬‬
3. Daniels, D. J. (2004). Ground Penetrating Radar. Institution of Engineering and Technology.
4. ACI Committee 222R-01. (2010). Protection of metals in concrete against corrosion, American Concrete Institute, Farmington Hills, MI.
5. Song, W., Popovics, J. S., Aldrin, J. C., and Shah, S. P. (2003). Measurement of surface wave transmission coefficient across surface-breaking cracks and notches in concrete. Journal of the Acoustical Society of America, 113(2), 717-725. doi:10.1121/1.1537709
6. Tallavo, F., Cascante, G., and Mahesh, P. (2009). Experimental and Numerical Analysis of MASW Tests for Detection of Buried Timber Trestles: Soil Dynamics and Earthquake Engineering, 29(1), 91-102.
7. Nasseri-Moghaddam A., Phillips C., Cascante G., and Hutchinson J. (2007). Effects of underground cavities on Rayleigh waves-numerical and experimental study. Soil Dyn Earthquake Eng, 27(4), 3000-13.
8. Hassan, A., Nasseri-Moghaddam, A., and Cascante, G. (2011). Use of numerical simulation for the identification of underground voids using the MASW test: in Proceedings: 14th PanAm CGS Geotechnical Conference.

9. Kirlangic, A. S., Cascante, C., and Polak, M. (2016). Assessment of concrete beams with irregular defects using surface waves. ACI Materials, 113(1), 73-81.
10. Rodríguez-Roblero, M. J., Ayon, J. J., Cascante, G., Pandey, M. D., Alyousef, R., and Topper, T. (2019). Application of correlation analysis techniques to surface wave testing for the evaluation of reinforced concrete structural elements: NDT and E International, 102, 68-76. doi:10.1016/j.ndteint.2018.11.003.
11. Aggelis, D. G., Shiotani, T., and Polyzos, D. (2009). Characterization of surface crack depth and repair evaluation using Rayleigh waves. Cement & Concrete Composites, 31 (1), 77–83.
12. Zerwer, A., Polak, M., and Santamarina, J. C. (2003). Rayleigh Wave Propagation for the Detection of Near Surface Discontinuities: Finite Element Study. Journal of Nondestructive Evaluation, (22)2, 39-52.
13. Zerwer, A., Polak, M., and Santamarina, J. C. (2005) Detection of Surface Breaking Cracks in Concrete Members Using Rayleigh Waves. Journal of Environmental & Engineering Geophysics, 10(3), 295-306.
14. Yang, Y., Cascante, G., and Polak, M. (2009). Depth detection of surface-breaking cracks in concrete plates using fundamental Lamb modes. NDT & E International, 42(6), 501-512.
15. Kirlangic, A. S., Cascante, C., and Polak, M. (2015). Condition Assessment of Cementitious Materials Using Surface Waves in Ultrasonic Frequency Range. ASTM International Geotechnical Testing Journal, 38(2), 1-11.
16. Aggelis, D. G., Leonidou, E., and Matikas, T. E. (2012). Subsurface crack determination by one-sided ultrasonic measurements. Cement and Concrete Composites, 34(2), 140-146. doi:10.1016/j.cemconcomp.2011.09.017
17. Richart, F. E. Jr., Hall, J. R. and Woods, R. D. (1970). Vibrations of Soil and foundations. Prentice-Hall, Englewood Cliffs, New Jersey.
18. Park, C. B., Miller, R. D., and Xia, J. (1997). Multichannel Analysis of Surface Waves, Kansas Geological Survey, Lawrence, KS.
19. EN 14651. (2005). Test method for metallic fibre concrete – Measuring the flexural tensile strength.
20. EN 12390-3. (2019). Testing hardened concrete – Part 3: Compressive strength of test specimens.
21. Addison, P. (2002). The Illustrated Wavelet Transform Handbook: Introductory Theory and Applications in Science, Institute of Physics Publishing, Bristol and Philadelphia.
22. Mallat, S. G. (1989). A theory for multiresolution signal decomposition: The wavelet representation. IEEE Transactions on Pattern Analysis and Machine Intelligence, 11(7), 674-693.
23. MATLAB. (2010). version 7.10.0 (R2010a). Natick, Massachusetts: The MathWorks Inc.
24. Kirlangic, A. S., Cascante, G., and Salsali, H. (2020). New Diagnostic Index Based on Surface Waves: Feasibility Study on Concrete Digester Tank. Journal of Performance of Constructed Facilities, 34(6). doi:10.1061/(ASCE)CF.1943-5509.0001522.
25. Graff, K. F. (1975). Wave Motion in Elastic Solids, Ohio State University Press, Belfast.
26. Ploix M-A., Garnier, V., Breysse, D., and Moysan, J. (2011). NDE data fusion to improve the evaluation of concrete structures. NDT E Int, 44(5), 442-448. doi:10.1016/j.ndteint.2011.04.006.