## 3 Analysis of Factors Affecting Flexural Performance of Reinforced Beams
### Validation of the Bending Load Capacity Formula  
To verify the correctness of the formula for calculating the flexural bearing capacity of reinforced concrete beams strengthened with FRP grids established in this paper, the test data in the literature [9; 18; 19; 20; 21; 22] were collected. All the test beams in the table were rectangular reinforced concrete simply supported beams, which were strengthened with FRP grids, and peeling failure occurred. The FRP grid debonding strain and ultimate load of the test beam are compared with the values calculated by Formulas (18) and (26). The results are shown in Table 7.  
As can be seen from Table 7, the mean, standard deviation, and coefficient of variation of the ratio of the test value of the debonding strain of the reinforced beam to the calculated value are 1.00, 0.076, and 0.076, and the mean, standard deviation, and coefficient of  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Beam ID** & \(\epsilon_{deb,calculated}\) & \(\epsilon_{deb,experimental}\) & \(\epsilon_{deb,calculated}\) & \(P_{u,calculated}\) & \(P_{u,experimental}\) & \(P_{u,experimental}\) \\  & & \(\frac{\epsilon_{deb,calculated}}{a}\) & \(\frac{\epsilon_{deb,calculated}}{a}\) & (\(\mathbf{kN}\)) & (\(\mathbf{kN}\)) & \(P_{u,calculated}\) \\ \hline II-12 [9] & 0.00976 & 0.00901 & 0.92 & 95.4 & 104.8 & 1.10 \\ V12 [9] & 0.00754 & 0.00812 & 1.08 & 120.1 & 117.6 & 0.98 \\ ROH [18] & 0.00573 & 0.00539 & 0.94 & 223.6 & 204.0 & 0.91 \\ MTF2 [19] & 0.00904 & 0.01002 & 1.11 & 169.3 & 155.2 & 0.92 \\ A2 [20] & 0.00740 & 0.00720 & 0.97 & 205.2 & 190.3 & 0.93 \\ S2-T1-P2-2 [21] & 0.01207 & 0.01150 & 0.95 & 71.7 & 66 & 0.92 \\ H\_4\_X [22] & 0.00744 & 0.00800 & 1.08 & 106.3 & 96.8 & 0.91 \\ \hline Average value & & & 1.00 & & & 0.96 \\ Standard deviation & & & 0.076 & & & 0.067 \\ Coefficient of variation & & & 0.076 & & & 0.067 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Validation of Formulas (18) and (26) for FRP grid debonding strain and flexural capacity of reinforced beams.  
Figure 13: Stress–strain distribution of reinforced beam section. (**a**) Cross-section. (**b**) Cross-section strain distribution. (**c**) Cross-section combined force distribution.  
variation of the ratio of the test value of the flexural capacity to the calculated value are 0.96, 0.067, and 0. 067. The overall agreement is better, but there is still a certain degree of error, which is considered by the author to be the reason for the error. The author believes that the reasons for the error are as follows:  
1. The bending capacity calculation formula of FRP grid-PCM-composite-strengthened reinforced concrete beams established in this paper is based on certain assumptions, so there is a certain error between the calculated value and the actual bending capacity of the reinforced beams.
2. When establishing the FRP grid peeling strain formula, only the case of peeling at the interface between the composite layer and the concrete is considered, which will be different from the interface when peeling damage occurs in the actual test reinforced beam.  
In summary, the formula established in this paper for calculating the peeling strain of FRP grid-reinforced RC beams with the occurrence of composite layer peeling damage has certain feasibility and can provide a certain theoretical basis for calculating or evaluating the flexural load capacity of FRP grid-reinforced concrete beams, but the applicability of the formula still needs more FRP grid-reinforced research and experimental data to be optimized.