PSI - Issue 64

Mehdi Aghabagloo et al. / Procedia Structural Integrity 64 (2024) 1516–1523 Mehdi Aghabagloo/ Structural Integrity Procedia 00 (2019) 000 – 000

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(black solid line) falls within the bond-slip laws of EBR (purple solid line) and HB (blue solid line). Although some discrepancies exist, the combined bond-slip law correctly captures/represents the main contributions of the anchoring system. As commented before, the discrepancies existing before the plateau (friction) stage are due to the fact of the interface being already smoothed at the initiation of the HB post-failure test. Moreover, Fig. 5b shows the comparison between the experimental load-slip response of the HB specimen (blue dashed line) and the load-slip response predicted by assuming the “added” bond -slip law (black dashed line). The agreement between the two plots indicates that the global performance of the joint is correctly predicted, with a slight underestimation of the maximum load. This difference can be attributed to the differences in the bond-slip law before the plateau (friction) stage highlighted before.

Fig.5 Comparison of a) bond-slip laws and b) load-slip curves

5. Conclusions In this paper, the bond performance of EBR and HB CFRP-to-concrete interfaces was experimentally studied through single shear tests, and experimental results were used to perform a numerical analysis on the contribution of the different bond mechanisms acting in a HB CFRP strengthening system. Further experimental results are required to validate the findings presented in this work. However, the following conclusions can be drawn from this study: • HB-CFRP strengthening technique enhanced the bonding performance of EB and produced an increase of 186% in the load-carrying capacity of the bonded joint. Although failure mode was cohesive failure in concrete for the two cases, a smoother debonded surface was visible for the HB specimen. • A novel methodology was applied to numerically predict the corresponding bond-slip laws. Numerical predictions showed good agreement with bond-slip laws experimentally derived at different locations along the bonded length. • Bond-slip law obtained in the HB post-failure specimen approached the plateau stage in the bond-slip law of HB specimen, thus demonstrating that the plateau corresponded to friction mechanism being induced by the compressive stresses of the anchoring system. • The addition of the bond-slip curves of the EBR and the HB post-failure specimens resembled that of the HB specimen. This opens ways to examine how the different anchoring parameters (i.e. width and thickness of the anchor and torque applied to the bolts) influence the performance of the anchoring system. 6. Acknowledgement The authors acknowledge the support provided by the Spanish Ministry of Science, Innovation and Universities through the project PID2020-119015GB-C22 funded by MICIU/AEI/10.13039/501100011033; M.A. and A.C. acknowledge the support of the Generalitat de Catalunya through the predoctoral program AGAUR-FI and the FSE+ (ref. IFUdG 2021/01 and FISDU2020, respectively); L.C. acknowledges the grant RYC2021-032171-I funded by MICIU/AEI/ 10.13039/501100011033 and by European Union NextGenerationEU/PRTR. The authors also wish to acknowledge the support of S&P Clever Reinforcement Ibérica Lda for supplying the laminates and the epoxy adhesive used in this study.