Issue 38

I. N. Shardakov et alii, Frattura ed Integrità Strutturale, 38 (2016) 331-338; DOI: 10.3221/IGF-ESIS.38.43 331 Delamination of carbon-fiber strengthening layer from concrete beam during deformation (infrared thermography) I. N. Shardakov, A. P. Shestakov Institute of Continuous Media Mechanics of the Ural Branch of Russian Academy of Science (ICMM UB RAS), Korolev str., 1, Perm, 614013, Russia. shardakov@icmm.ru, shap@icmm.ru A.A. Bykov Perm National Research Polytechnic University, Komsomolsky ave., 29, Perm, 614990, Russia violentharpy@ya.ru A BSTRACT . Technology of strengthening reinforced concrete structures with composite materials has found wide application. The effectiveness of strengthening of concrete structures with externally bonded reinforcement is supported by a great deal of experimental evidence. However, the problem of serviceability of such structures has not been adequately explored. The present work describes the results of experimental studies on the load- carrying capacity of concrete beams strengthened with carbon fiber reinforced plastic (CFRP). Special emphasis is placed on studying the debonding of the strengthening layer from the concrete surface and analyzing its influence on the load-carrying capacity of beams. Infrared thermography is used to detect the first signs of debonding and to assess the debond growth rate. K EYWORDS . Carbon fiber reinforced plastic; Reinforced concrete beams; Strengthening; Intermediate crack debonding; Infrared thermography; Quality control; Non-destructive testing methods. Citation: Shardakov, I. N., Bykov, A.A., Shestakov, A. P., Delamination of carbon- fiber strengthening layer from concrete beam during deformation (infrared thermography), Frattura ed Integrità Strutturale, 38 (2016) 331-338. Received: 02.06.2016 Accepted: 30.08.2016 Published: 01.10.2016 Copyright: © 2016 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION t present, the technology of strengthening reinforced concrete structures with composite materials is extensively used in the constructional industry. There are many studies supporting the efficiency of strengthening of concrete structures with externally bonded reinforcement, but the evaluation of serviceability of such structures is still the problem to be solved. There are several possible options of failure of composite reinforced concrete beams [1]: rupture of fiber-reinforced plastic, crushing of compressive concrete, shear failure, concrete cover separation, plate and interfacial debonding, and intermediate crack induced interfacial debonding. In designing structures reinforced with composite materials, the liming state of such structures is considered to be the state of structure deformation, at which the debonding of the composite material from the concrete surface occurs. According to Russian (SP 164.1325800.2014, [2]) and American (ACI 440.2R- A