Using digital image correlation to evaluate fatigue behavior of strengthened reinforced concrete beams

The fatigue behavior of reinforced concrete beams strengthened with externally bonded carbon fiber reinforced polymer (EBR) plates and near-surface mounted (NSM) bars has been investigated using a digital image correlation (DIC) technique. Displacement fields obtained from digital images recorded during specific load cycles in fatigue tests are analyzed to provide information on crack width, beam deflection and curvature, and major principal strains to enable crack detection. The results obtained in this way were compared to data gathered using conventional sensors, revealing that the DIC technique provided very accurate and detailed information, which is not possible to obtain using conventional techniques. The experimental results for plate-strengthened, bar-strengthened and unstrengthened beams are discussed.