PSI - Issue 10

M. Petrov et al. / Procedia Structural Integrity 10 (2018) 303–310

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M. Petrov et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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The experimental results presented in Fig.8 shows that the energy attenuation coefficient of electric responses registered from concrete reinforced with steel cage is most significantly increased at the stage preceding the catastrophic destruction of the sample. Similar results were obtained when compressing samples of concrete reinforced with one and two reinforcing bars, with the only difference is that the attenuation coefficient in these samples increases less rapidly.

4. Conclusion

The purpose of the research presented in this paper is to study the patterns of changes in the parameters of the electric response and the elastic and mechanical characteristics of the reinforced concrete during compression. The results of theoretical and experimental studies have shown that the differences in the distribution of internal mechanical stresses in reinforced concrete with different types of reinforcement, established using numerical simulation are in good agreement with the changing of stress-strain dependencies and concrete strength under uniaxial compression. The main diagnostic criteria are proposed based on the conducted studies. Using the diagnostic criteria, it is possible to evaluate the destruction processes in reinforced concrete under uniaxial compression. These diagnostic criteria are, reduction in the maximum cross-correlation coefficient of the analyzed signal spectrum registered during mechanical loading with the spectrum registered prior to loading up to 0.4 - 0.5, and stepwise changing in the shift (in frequency) at which the maximum coefficient of cross-correlation is observed; reduction of spectrum gravity center by 20 - 40%; and increasing in energy attenuation coefficient of electric response by 1.5 - 2.5 times. Consequently, the crack formation processes in concrete under the external compressive load can be evaluated by analyzing the group of diagnostic parameters. The experimental results have shown that the proposed method can be used to monitor the damages development in reinforced concrete under uniaxial compression. Alam, S.Y., Loukili, A., 2017. Transition from energy dissipation to crack openings during continuum – discontinuum fracture of concrete. International Journal of Fracture 206, 49-66. Dai, H., Gallo, G.J., Schumacher, T., Thostenson, E.T., 2016. A novel methodology for spatial damage detection and imaging using a distributed carbon nanotube-based composite sensor combined with electrical impedance tomography. Journal of Nondestructive Evaluation 35, 26. Fursa, T.V., Dann, D.D., Petrov, M.V., Lykov, A.E., 2017a. Evaluation of damage in concrete under uniaxial compression by measuring electric response to mechanical impact. Journal of Nondestructive Evaluation 36, 30. Fursa, T.V., Dann, D.D., Petrov, M.V., 2017b. Evaluation of freeze-thaw damage to reinforced concrete based on the parameters of electric response to mechanical impact. Construction and Building Materials 155, 451 – 462. Fursa, T.V., Utsyn, G.E., Dann, D.D., Petrov, M.V., 2017c. Development prospects for nondestructive testing of heterogeneous nonmetallic materials by the parameters of electrical response to a shock action. Russian Journal of Nondestructive Testing 53, 104-110. Gade, S.O., Alaca, B.B., Sause, M.G.R., 2017. Determination of crack surface orientation in carbon fibre reinforced polymers by measuring electromagnetic emission. Journal of Nondestructive Evaluation 36, 21. In, C.W., Schempp, F., Kim, J.Y., Jacobs, L.J., 2015. A fully non-contact, air-coupled ultrasonic measurement of surface breaking cracks in concrete. Journal of Nondestructive Evaluation 34, 272. Krzemień , K., Hager, I., 2015. Post-fire assessment of mechanical properties of concrete with the use of the impact-echo method. Construction and Building Materials 96, 155-163. Lin, Y., Sansalone, M., 1992. Transient response of thick circular and square subjected to transverse elastic impact. The Journal of the Acoustical Society of America 91, 885-893. Quiviger, A., Payan, C., Chaix, J.-F., Garnier, V., Salin, J., 2012. Effect of the presence and size of a real macro-crack on diffuse ultrasound in concrete. NDT & E International 45, 128-132. Song, H., Popovics, J.S., 2017. Characterization of steel-concrete interface bonding conditions using attenuation characteristics of guided waves. Cement and Concrete Composites 83, 111-124. Stergiopoulos, C., Stavrakas, I., Hloupis, G., Triantis, D., Vallianatos, F., 2013. Electrical and Acoustic Emissions in cement mortar beams subjected to mechanical loading up to fracture. Engineering Failure Analysis 35, 454-461. Acknowledgements This work was performed under Russian science foundation (Project №16 -19-10119). References