PSI - Issue 37

Haya H. Mhanna et al. / Procedia Structural Integrity 37 (2022) 359–366 Author name / Structural Integrity Procedia 00 (2019) 000 – 000 7 than 1.0. The CSA-S806.12 (2017) provide safe results ( ̅ =1.34) with least error values (MAE =24% and RMSE =22). Although the least standard deviation and CoV values for the anchored U-wraps are given by fib bulletin 90 (2019) guidelines, its predictions are unsafe with an average ratio of the experimental to predicted V f values less than 1.0 ( ̅ =0.85). This could be since fib bulletin 90 (2019) provisions allow the stress in the anchored laminates to be a ratio of the stress in the completely wrapped laminates with 90% as a maximum limit (implemented in this study). However, this limit should be determined through testing approval of the anchorage system and cannot be used for all types of anchors. The results provided in Table 4 show that all models provide underestimated (safe) results for all wrapping schemes on average, with all ̅ values greater than 1.0. The ACI440.2R-17 (2017) and TR55 (2000) provide the most conservative predictions with highest values of StD, CoV, MAE, and RMSE. Therefore, the provisions of ACI440.2R 17 (2017) and TR55 (2000), although are considered conservative and safe, but are the least accurate. Hence, the limitations (especially on the effective strain) in the ACI440.2R-17 (2017) and TR55 (2000) could be improved to better utilize the FRP capacity. Overall, fib bulletin 90 (2019) and CSA-S806.12 (2017) provisions were the most accurate in terms of having the least standard deviation and error values, and ̅ values very close to 1 (1.04 and 1.35, respectively). Although fib bulletin 90 (2019) guidelines displayed unsafe results for the anchored U-wraps, the average ( ̅ ) was very close to 1.0 (0.85). In addition, the inclusion of reduction factors will improve the results; hence, resulting in safe, accurate, and cost-efficient design. 6. Conclusions The accuracy of four design guidelines (ACI440.2R-17, CSA-S806.12, fib bulletin 90, and TR55) for evaluating the FRP contribution to shear capacity was assessed with comparison of an experimental database. The following conclusions were drawn: • All design provisions provided on average unsafe predictions for U-wrapped configuration. However, the results are reasonable considering that the strength reduction factors were not included in the analysis. • All guidelines overestimated the capacity (safe predictions) of completely wrapped configuration with the fib bulletin 90 providing the most accurate predictions and the TR55 the least (most conservative). • Fib bulletin 90 guidelines overestimated the capacity of anchored U-wrapped specimens on average but provided the most accurate results. CSA-S806.12 guidelines, on the other hand provided safe and accurate results for anchored specimens. • Overall, it can be concluded that fib bulletin 90 and CSA-S806.12 design guidelines could be safely used to effectively and efficiently design FRP shear strengthened beams. • The ACI440.2R-17 and TR55 provided safe and underestimated predictions. However, the results were inaccurate and very conservative. These provisions should improve the limitations on the effective strain in the FRP to improve the utilization of the FRP capacity. References Abuodeh, O. R., Abdalla, J. A., Hawileh, R. A. 2020. Prediction of shear strength and behavior of RC beams strengthened with externally bonded FRP sheets using machine learning techniques. Composite Structures 234, 111698. ACI440.2R-17. 2017. Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures. American Concrete Institute, Farmington Hills, U.S.A. Bae, S., Belarbi, A. 2013. Behavior of Various Anchorage Systems Used for Shear Strengthening of Concrete Structures with Externally Bonded FRP Sheets. Journal of Bridge Engineering 18, 837 – 847. Belarbi, A., Acun, B. 2013. FRP systems in shear strengthening of reinforced concrete structures. Procedia Engineering 57, 2 – 8. Bousselham, A., Chaallal, O. 2008. Mechanisms of shear resistance of concrete beams strengthened in shear with externally bonded FRP. Journal of Composites for Construction 12(5), 499 – 512. Cao, S. Y., Chen, J. F., Teng, J. G., Hao, Z., Chen, J. 2005. Debonding in RC Beams Shear Strengthened with Complete FRP Wraps. Journal of Composites for Construction 9(5), 417 – 428. Chen, G. M., Li, S. W., Fernando, D., Liu, P. C., Chen, J. F. 2017. Full-range FRP failure behaviour in RC beams shear-strengthened with FRP wraps. International Journal of Solids and Structures 125, 1 – 21. 365