# Novel Predictive Model of the Debonding Strength for Masonry Members Retrofitted with FRP
## 5 Conclusions  
In this study, GEP was applied to model the complex behavior of debonding strength of FRP strengthened masonry (SM) elements. The major focus of this research is to propose a novel formula for  
Figure 4: Comparison of the GEP model with existing methods in the prediction of the debonding force for the training data.  
Figure 5: Comparison of GEP model with existing methods in the prediction of the debonding force for the testing data.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Model**} & \multicolumn{2}{c}{**Training Data**} & \multicolumn{2}{c}{**Test Data**} \\ \cline{2-5}  & \(\mathbf{R^{2}}\) & **RMSE (root mean square errors)** & \(\mathbf{R^{2}}\) & **RMSE** \\ \hline Tanaka model & 0.1722 & 23,485.3 & 0.1088 & 16,711.0 \\ [PERSON] model & 0.8445 & 70,656.6 & 0.6723 & 54,877.9 \\ [PERSON] model & 0.0783 & 28,333.3 & 0.1179 & 28,139.8 \\ [PERSON] model & 0.4974 & 20,474.6 & 0.2124 & 14,444.9 \\ [PERSON] model & 0.4014 & 18,200.2 & 0.3190 & 13,263.4 \\ [PERSON] model & 0.6045 & 17,555.1 & 0.4898 & 12,535.5 \\ [PERSON] model & 0.9189 & 8309.8 & 0.8841 & 6471.9 \\ [PERSON] model & 0.2132 & 20,622.8 & 0.1624 & 14,723.3 \\ [PERSON] model & 0.3209 & 19,669.1 & 0.2833 & 13,847.4 \\ [PERSON] model & 0.2988 & 19,160.5 & 0.2168 & 14,304.8 \\ [PERSON] model & 0.0827 & 21,723.1 & 0.1204 & 15,851.3 \\ [PERSON] model & 0.5013 & 16,790.5 & 0.3837 & 12,609.5 \\ Present model & 0.9647 & 4013.1 & 0.9492 & 3801.7 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Training and testing results of existing models and GEP.  
determining the debonding resistance of FRP SM members as a function of various influencing factors. A reliable database including formerly published debonding strength of FRP SM members test results was used for developing the applied model. The suggested model used various important parameters (\(b_{p}\), \(t_{p}\), \(E_{p}\), \(f_{ut}\), \(b_{m}\), \(l_{b}\)) representing the behavior of the debonding strength as inputs. The GEP results revealed good agreement with the gathered experimental results. The performance of the GEP was compared to the twelve existing empirical models obtained in previous studies. GEP was found to be the best model in prediction of the debonding strength of retrofitted masonry members. Among the empirical models, Kashyap provided the best results. The optimal GEP model reduced the root mean square errors by 51.7% and 41.3% with respect to the best empirical model (Kashyap) in the training and test periods, respectively. The proposed GEP model can be applied in practical pre-planning and design purposes because it was obtained from experimental tests on beams with a wide range of geometrical and mechanical properties.  
This research was supported by a grant (15 TBIP-C093001-01) from Support for Infrastructure and transportation technology commercialization Program funded by Ministry of Land, Infrastructure and Transport of Korean government. The authors gratefully acknowledge this support.  
For research articles with several authors, a short paragraph specifying their individual contributions must be provided. The following statements should be used. [PERSON] and [PERSON] collected many experimental specimens and applied artificial tools to database and Prof. [PERSON] analyzed the data; [PERSON] contributed reagents/materials/analysis tools; [PERSON] wrote the paper.  
The authors declare no conflict of interest.