Issue 46

I. Shardakov et alii, Frattura ed Integrità Strutturale, 46 (2018) 383-390; DOI: 10.3221/IGF-ESIS.46.35 389 frequency of 3400 Hz (corresponding to the most intense vibrations) with the growth of damage in the structure. The first column corresponds to the defect-free structure, and the other columns – to the structures, in which the number of cracks increases. In this case, the value of the criterion increases markedly. Figure 8 : Criterion  * 0 / k K a a at different stages of cracking. C ONCLUSION n this work, verification of a mathematical model of dynamic processes in a reinforced concrete structure was carried out within the framework of viscoelasticity. A comparison of the experimental and calculated data has demonstrated that this model can be effectively used to describe with sufficient accuracy the propagation of vibration processes initiated by external, locally applied impact loads. A series of numerical experiments performed on the basis of the mathematical model allowed us to investigate changes in the vibration parameters of the RC structure, in which the process of crack formation has started. As a parameter, characterizing the process of crack nucleation, we used the ratio of the amplitude values of the Fourier transform in the defect and defect-free structure obtained at the frequency of the most severe vibrations. On the whole, the results of this study served to determine the substance of the desired algorithm for implementing the vibration diagnosis of reinforced concrete structures with the aim to control the process of crack formation. A CKNOWLEDGMENTS he research was performed at the Institute of Continuous Media Mechanics Ural Branch of Russian Academy of Science with the support of the Russian Science Foundation (project №14-29-00172). R EFERENCES [1] Verma, S.K., Bhadauria, S.S. and Akhtar, S. (2013). Review of non destructive testing methods for condition monitoring of concrete structures, J. Constr. Eng, 834572. DOI: 10.1155/2013/834572. [2] Fan, W. and Qiao, P. (2011). Vibration-based damage identification methods: a review and comparative study, Structural Health Monitoring. 10(1), pp. 83-111. DOI: 10.1177/1475921710365419. [3] Stepinski, T., Uhl, T., and Staszewski, W. (2013). Advanced structural damage detection: from theory to engineering applications., John Wiley & Sons. DOI:10.1002/9781118536148. [4] Wang, L. and Chan, T.H.T. (2009). Review of vibration-based damage detection and condition assessment of bridge structures using structural health monitoring., Proc. of the second infrastructure theme postgraduate conference. Queensland University of Technology. Paper ID 26738. http://eprints.qut.edu.au/. [5] Quaranta, G., Carbonu, B. and Lacarbonara, W. (2014). Damage detection by modal curvatures: numerical issues, J. Vibr. Contr. 22 (7) pp. 1913-1927. DOI: 10.1177/1077546314545528. [6] Bykov, A.A., Matveenko, V.P., Serovaev, G.S., Shardakov, I.N. and Shestakov, A.P. (2015). Mathematical modeling of vibration processes in reinforced concrete structures for setting up crack initiation monitoring, Mech. Solids, 50 (2), pp. 160-170. DOI: 10.3103/S0025654415020053. I T