A study of using full-field thermographic technique to characterize the shear behaviour of externally bonded CFRP-concrete composites

This paper present the results of a study on the behavior of CFRP-concrete beam composite when it is subject to a continuous shear stress using full-field thermography. Self-referencing thermal contrast and half-maximum methods were adopted to process the entire series of time-lapsed thermograms captured during the process. The distributions of pixel values contained in the processed thermograms were interpreted to represent the elastic, the elastic-softening, the elastic-softening-rupture and the softening-rupture stages experienced by the composite. These distributions were further analyzed quantitatively to evaluate the longitudinal rupture fraction and the effect of the applied shear stress on the extent of the ruptured areas. Based on these findings, the rupture areas were quantified and were found to increase significantly when a higher shear stress was applied. The information provided by the full-field thermographic data have potential to be used as additional data (tip of rupture, ruptured and softened areas) to supplement constitutive equations and bond-slip models in fracture mechanics.