PSI - Issue 64

Veronica Bertolli et al. / Procedia Structural Integrity 64 (2024) 1033–1040 1039 Veronica Bertolli, Lesley H. Sneed, Francesco Focacci, Tommaso D’Antino/ Structural Integrity Procedia 00 (2019) 000–000 7

( r =0.945), highlighting the good accuracy of the model. For the latter, r was equal to 2.131, which entails for a significant underestimation of the experimental results. Even though only four beams were strengthened with basalt fibers, both models presented the lowest values of CoV in this case. The model by CNR-DT 215 (2018) had the highest value of CoV for the case of steel fibers (CoV=0.574), whereas the model by ACI 549.4R (2020) for the case of carbon fibers (CoV=1.485). Large values of CoV were attained by both models for all fiber types, highlighting the high variability of results. With the aim of providing a design model able to accurately reproduce the experimental shear strength contribution of the U-wrapped FRCM, further test results are needed to increase the database and provide reliable values of model partial factors. The experimental shear strength contributions of the FRCM V f,exp are compared with the analytical predictions V f,an of models by CNR-DT 215 (2018) and ACI 549.4R (2020) in Fig. 3 first considering specimens of the same fiber type and then considering all specimens in the database. The model by ACI 549.4R (2020) tended to underestimate the value of V f,exp . This could be attributed to the use of the tensile modulus of cracked FRCM, E FRCM , or to the limitation imposed to the effective strain  fe (see Eq. (5)), which in turn entailed for a small contribution of the FRCM. The model by CNR-DT 215 (2018), able to take into account the actual bond behavior of the specific FRCM studied, generally provided accurate results. 4. Conclusions In this paper, the models by CNR-DT 215 (2018) and ACI-549.4R (2020) for U-wrapped FRCM shear strengthened RC beams were used to compute the shear strength of 103 FRCM shear strengthened RC beams collected from the literature. Comparison between the predictions of the two models showed that CNR-DT 215 (2018) provided good approximations of the experimental results, whereas quite conservative results were obtained with the model by ACI 549.4R (2020). The highest accuracy was attained with model CNR-DT 215 (2018) for beams strengthened with carbon FRCM. The high values of CoV obtained by both models underlined the high variability of the results. Considering the large number of parameters influencing the contribution provided by the EB FRCM on the shear strength of RC beams, further experimental results are needed to better identify their role. Acknowledgements Drs. D’Antino and Focacci acknowledge the support of the DPC-ReLUIS 2024-2026 project (WP 14) funded by the Italian Department of Civil Protection. References ACI Committee 318, 2019. Building code requirements for structural concrete (ACI 318-19) and commentary (ACI 318R-19). ACI PRC-318R 19, ACI, Farmington Hills, 48331 MI. ACI Committee 440, 2017. Guide to Design and Construction of Externally Bonded FRP Systems for Repair and Strengthening Concrete Structures. ACI PRC-440.2-17., ACI, Farmington Hills, 48331 MI. ACI Committee 440, 2023. Guide to Design and Construction of Externally Bonded FRP Systems for Repair and Strengthening Concrete Structures. ACI PRC-440.2-23., ACI, Farmington Hills, 48331 MI. ACI Committee 549, 2020. Guide to Design and Construction of Externally Bonded Fabric-Reinforced Cementitious Matrix and Steel Reinforced Grout Systems for Repair and Strengthening of Concrete Structures. ACI PRC-549.4-20, ACI, Farmington Hills, 48331 MI. Arboleda, D., Carozzi, F. G., Nanni, A., and Poggi, C., 2016. Testing procedures for the uniaxial tensile characterization of fabric-reinforced cementitious matrix composites, Journal of Composites for Construction, 20(3). Bertolli, V., and D’Antino, T., 2022. Modeling the behavior of externally bonded reinforcement using a rigid-trilinear cohesive material law, International Journal of Solids and Structures, 248, 111641. Bertolli, V., Signorini, C., Nobili, A., and D’Antino, T., 2023. Influence of severe thermal preconditioning on the bond between carbon FRCM and masonry substrate: Effect of textile pre-impregnation, Construction and Building Materials, 409, 134028. Bertolli, V., Sneed, L. H., Focacci, F., and D’Antino, T., Shear strengthening of RC beams with U-wrapped FRCM composites: state of art and assessment of available analytical models, Journal of Composites for Construction - under review. Brückner, A., Ortlepp, R., and Curbach, M., 2006. Textile reinforced concrete for strengthening in bending and shear, Materials and Structures, 39(8), 741–8. Brückner, A., Ortlepp, R., and Curbach, M., 2008. Anchoring of shear strengthening for T-beams made of textile reinforced concrete (TRC), Materials and Structures, 41(2), 407–18. Carloni, C., and Focacci, F., 2016. FRP-masonry interfacial debonding: An energy balance approach to determine the influence of the mortar joints, European Journal of Mechanics, A/Solids, 55, 122–33.