PSI - Issue 54

Ahmed Selim et al. / Procedia Structural Integrity 54 (2024) 601–608 Selim et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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3. Finite element results and discussion A comparison of the FE predictions for the load-deflection response curves is presented in Fig. 5. The externally bonded prism with the FRP laminate exhibited a linear elastic behavior, indicating premature debonding of the laminate. This observation aligns with the fact that the load-deflection curve in (a) lacks a plastic region, in contrast to (b), which resembles the behavior of concrete undergoing compressive cracking. Fig. 6 provides front and bottom views of the FE prediction for debonding failure in the prism externally bonded with the FRP laminate. On the other hand, an indicator of delayed debonding behavior for the prism with the grooved system is the substantial increase in stiffness, as evident when comparing the linear regions in Fig. 5 (a) and (b). To emphasize, Fig. 7 displays the front and bottom views of the FE prediction of delayed debonding in the prism externally bonded with near-surface mounted FRP laminate. The predictable ultimate load for the prism externally bonded with the FRP laminate is 2213 N. Conversely, the FE results reveal that the predictable ultimate load for the prism externally bonded with near-surface mounted FRP laminate is 2341 N, indicating a 6% increase in the strength of the grooved prism. It's important to note that a higher increase in strength was expected compared to the FE results. Several factors may have limited the efficiency of the new grooved system to provide a higher percent increase in the load-carrying capacity. One of these factors is the removal of compression and tensile damage properties in the concrete-damaged plasticity model. This may have hindered the software's ability to simulate concrete cracking and performance accurately. Furthermore, it's crucial to highlight that the use of low-strength concrete in this study may have led to the dominant failure mode in the prism externally bonded with near-surface mounted FRP laminate being concrete crushing. In other words, if higher-strength concrete had been employed, the effectiveness of grooving the FRP laminate would have been more pronounced.

Fig. 5. Load-Deflection curve: (a) prism externally bonded with FRP laminate (b) prism externally bonded with near surface mounted FRP laminate

Fig. 6. Front and bottom view for FE prediction for debonding failure for prism externally bonded with FRP laminate