Influence of different bonding and wrapping techniques on performance of beams strengthened in shear using CFRP reinforcement

Promising results have been obtained from flexural strengthening of concrete elements using the grooving method in its special form of externally bonded reinforcement in grooves (EBRIG) to postpone CFRP debonding and load carrying capacity enhancement. Drawing upon these results, the present study aims to investigate the influence of the EBRIG and EBR methods used for shear strengthening of structural members when used with different techniques of installing CFRP sheets to provide sufficient bonding between CFRP sheets and the concrete substrate. For the purposes of this study, seven concrete beam specimens, 120 × 160 × 1400 mm in size, were cast and subjected to the 4-point loading test. External shear anchorages were provided for each span of the beams separately, therefore, each specimen was tested in two rounds and a total of 14 tests were performed. One specimen was used as the control beam without any strengthening and six were strengthened using either the EBR or the EBRIG methods. Results showed that, compared to control specimen without CFRP strengthening the EBRIG and EBR method combined with full wrapping technique led to a load carrying capacity enhancement up to an average percentage about 148% and 141%, and moreover, as a significant result the failure mechanism was observed to change from a brittle shear failure by utilizing EBR method to the desirable flexural mode by utilizing EBRIG method.