Phase Analysis of Data from Air-Coupled Impact Echo Testing of Concrete Decks

Impact-echo is a nondestructive testing method used to detect internal defects, primarily delamination, in concrete elements. The amplitude spectrum is commonly used to determine the thickness frequency that gives information of the element thickness or is an indication of the presence of a defect or anomaly. However, the amplitude spectrum is usually contaminated with multiple modes, and the localization of the thickness frequency is not straightforward. Furthermore, preprocessing is required to remove the unwanted wave components, and to eliminate or reduce noise. The phase spectrum of the impact echo signal contains information about the dispersion properties. Recently, these properties were used to determine the dominant response frequency, which corresponds to the zero-group velocity mode (S1-ZGV). This study examines the use of the phase spectrum of impact-echo signals, recorded from multiple air-coupled sensors, to locate internal defects in concrete elements. The phase spectra of these signals are stacked together to obtain a 2D frequency-sensor offset profile. This profile shows a constant phase at the thickness mode frequency. The performance of the method is successfully examined on decks with shallow and deep delamination, and without delamination. Furthermore, an algorithm is developed to automatically locate the frequencies corresponding to a constant phase, making the proposed method suitable for automated detection and characterization of delamination.

References

 

  • M. J. Sansalone and W. B. Streett, Impact-Echo-Nondestructive Evaluation of Concrete and Masonry, New York: Bullbrier Press, 1997.
  • Gibson A and Popovics J S 2005, “ Lamb wave basis for impact-echo method analysis,” J. Eng. Mech. 131, 438-43.
  • Hajin Choi and H. Azari, “ Guided wave analysis of air-coupled impact-echo in concrete slab,” Computers and Concrete, Vol. 20, No, 3, 2017, pp. 257-262
  • Groschup, R. and C. Grosse, “ MEMS Microphone Array Sensor for Air-Coupled Impact-Echo,” Sensors, 2015. 15(7): pp. 14932-14945.
  • Ham, S.; Popovics, J., “Application of Micro-Electro-Mechanical Sensors Contactless NDT of Concrete Structures,” Sensors, 2015, 15, pp. 9078–9096.
  • Kee, S.-H., and Gucunski, N., (2016). “Interpretation of flexural vibration modes from impact-echo testing.” J. Infrastruct. Syst, 10.1061 /(ASCE)IS.1943-555X.0000291, 04016009.
  • Epp T and Cha YJ., “ Air-coupled impact-echo damage detection in reinforced concrete using wavelet transforms,” Smart Mater Struct 2017; 26(2): 025018.
  • Oh, T.; Kee, S.; Arndt, R.W.; Popovics, J.S.; Zhu, J. Comparison of NDT Methods for Assessment of a Concrete Bridge Deck. J. Eng. Mech. 2013, 139, 305–314.
  • S. W. Shin, J. S. Popovics and T. Oh, "Cost Effective Air-coupled Impact-Echo Sensing for Rapid Detection of Delamination Damage in Concrete Structures", Advances in Structural Engineering, Vol. 15, No. 6, pp. 887-896, 2012.
  • Dai, X.W.; Zhu, J.Y.; Tsai, Y.T.; Haberman, M.R., “Use of parabolic reflector to amplify in-air signals generated during Impact-Echo testing,” J. Acoust. Soc. Am. 2011, 130, El167–El172.
  • Gilbert Strang, 2009, Introduction to Linear Algebra, fourth edition, Wellesley-Cambridge Press.
  • Baggens, O.; Ryden, N., “Systematic errors in Impact-Echo thickness estimation due to near field effects,” NDT E Int. 2015, 69, 16–27.
Metrics
Usage Shares
Total Views
33 Page Views
Total Shares
0 Tweets
33
0 PDF Downloads
0
0 Facebook Shares
Total Usage
33