## 4 Validation of the Established FE Models
### Deflection Behavior, Ultimate Capacity, and FRP Strain  
Comparisons between the experimental midspan deflections of the beams and the theoretical results based on the FE models are displayed in Figure 16. According to the curve segments divided in [10], generally, the experimental and measured deflections followed the same trend in the precracking and postcracking stages. For GFRP-reinforced beams that experienced concrete crushing, the FE models yielded a stage that corresponded to the crushing process, which was in agreement with the test results. However, the estimations with respect to the deflection value evidenced discrepancies in this stage. In the case of the steel reinforced beam LC-S-4#10.62 (Figure 16), the FE model provided reasonable predictions during the entire loading period.  
Based on [PERSON] et al.'s recommendation [31], the 30% of \(M_{u}\) obtained by the test results was selected as the service load to evaluate the accuracy of the established FE models. Table 4 lists the \(\Delta_{s}\) according to the FE models and the experimental-to-predicted \(\Delta_{s}\) (\(\Delta_{s,\mathrm{Exp}}/\Delta_{s,\mathrm{FEM}}\)). The models predicted the \(\Delta_{s}\) with a mean \(\Delta_{s,\mathrm{Exp}}/\Delta_{s,\mathrm{FEM}}\) of 1.09 \(\pm\) 0.19, while ACI 440.1R [33], CSA S806 [34], and GB 50608 [32] provided estimations with average \(\Delta_{s,\mathrm{Exp}}/\Delta_{s,\mathrm{FEM}}\) values of 0.94 \(\pm\) 0.38, 0.57 \(\pm\) 0.26, and 1.97 \(\pm\) 0.40, respectively, as calculated in [10]. The estimations based on the FE models closely matched the measured deflections at service load with small dispersion, which supported the validity of the developed FE model in predicting the stiffness of LWAC and SFLC beams reinforced with GFRP bars.  
Table 4 summarizes the \(M_{u}\) computed by the FE method and compared the predictions with the experimental results. The established FE models yielded accurate \(M_{u}\) predictions with an average experimental-to-predicted ratio (\(M_{u,\mathrm{Exp}}/M_{u,\mathrm{FEM}}\)) of 1.04 \(\pm\) 0.17. While the \(M_{u,\mathrm{Exp}}/M_{u,\mathrm{FEM}}\) values that were obtained according to ACI 440.1R [33], CSA S806 [34], and GB 50608 [32] were 0.94 \(\pm\) 0.38, 1.01 \(\pm\) 0.39, 0.94 \(\pm\) 0.16, as reported in [10]. In addition, as shown in Figure 17, the similar evolution of strain in GFRP reinforcement suggested that the definition of tension stiffening applied in this study was applicable for such beams.  
However, the models for LC-G-6#9.87 and SLC-G-6#9.87 produced some relatively larger deviations in predicting the ultimate capacity and deflection of beams. The discreteness in the mechanical properties of the concrete and GFRP bars was responsible for this difference between the simulation and test results. Notwithstanding these errors, the whole moment-deflection responses and evolution of FRP strain still presented an acceptability of FE models.  
Figure 15: Crack patterns, strain of GFRP bars, and the final failure mode of FE model SLC–G–3#13.77.  
Figure 16: Comparison of moment-deflection curves: (**a**) LC–G–5#13.77; (**b**) SLC–G–5#13.77; (**c**) LC–G–8#13.77; (**d**) SLC–G–8#13.77; (**e**) LC–G–3#13.77; (**f**) SLC–G–3#13.77; (**g**) LC–G–6#9.87; (**h**) SLC–G–6#9.87; (**i**) LC–G–4#9.87; and (**j**) LC–S–4#10.62.  
The modeling and predictions of three specimens reinforced with GFRP bars yielding different failure modes, and the specimens without GFRP bars were analyzed to illustrate the results of the FE method. Figure 18 presents the historical energy of the four models. The kinetic energy of the four models was negligible; therefore, the influence of kinetic energy on the results was insignificant. Similarly, the results of all 10 models were not found to be greatly affected by kinetic energy, yet the diagrams for these were not presented owing to the length limitation.