# Assessment of Existing Bond Models for Externally Bonded SRP Composites
## 4 Results and Discussion
### Assessment of Design Guidelines  
To evaluate the reliability of design guidelines for the bond prediction of SRP, a demerit points classification proposed by [PERSON] (2018) was used. This scale allowed considering the safety and accuracy of design procedures by weighting the ratio between the ultimate bond strength, estimated theoretically and measured experimentally (\(F_{ub,predictal}/F_{ub,test}\)). Table 8 presents the classification adopted in this study based on the original values proposed by [PERSON]. The results of bond comparisons were classified into appropriate categories, as shown in Table 8, and the products were then multiplied by the appropriate demerit points classification (DPC) and summed up. The number of results assigned to the categories and the summed DPC is shown in Tables 9 and 10. A lower overall DPC means that the model under consideration was more reliable. In the case of SRP bonded to concrete, the lowest total demerit points (111 points) presented the Swiss Standard SIA 166/2004. _Fib_ bulletin 14 achieved a slightly worse result (115 points); however, this was mainly due to a small number of overestimated results. In terms of the number of the most accurate predictions, there were SIA166, Italian code CNR-DT200, and _fib_ bulletin 90. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Model**} & \multirow{2}{*}{**SRP**} & \multicolumn{3}{c}{**CFRP**} \\ \cline{3-5}  & & **[PERSON] et al. (2018)** & **[PERSON] et al. (2018)** & **[PERSON] et al. (2018)** \\ \hline [PERSON] (2018) & 0.699 & 0.48 & 0.68 & 0.98 \\ [PERSON] and [PERSON] (2018) & 0.746 & 0.476 & & 0.94 \\ [PERSON] et al. (2018) & 1.14 & 0.929 & 0.95 & 1.25 \\ [PERSON] (2018) & 0.761 & 0.761 & & \\ [PERSON] (2018) & 0.763 & 0.73 & 0.87 & \\ [PERSON] and [PERSON] (2018) & 0.980 & 1.12 & 1.10 & 1.23 \\ [PERSON] and [PERSON] (2018) & 0.763 & 0.763 & & \\ [PERSON] et al. (2018) & 0.873 & 0.819 & & \\ [PERSON] et al. (2018) & 1.55 & 1.49 & & \\ [PERSON] and [PERSON] (2018) & 0.937 & 0.718 & & \\ [PERSON] et al. (2018) & 0.754 & 0.798 & 0.92 & 0.76 \\ [PERSON] et al. (2018) & 0.528 & 0.841 & 0.94 & 0.89 \\ [PERSON] (2018) & 2.00 & 1.19 & & \\ [PERSON] et al. (2018) & 1.81 & 1.28 & 1.45 & 1.03 \\ [PERSON] and [PERSON] (2018) & 0.882 & 0.857 & 0.89 & 0.91 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Predicted to experimental bond strength ratios for SRP composites and carbon fiber reinforced polymer (CFRP) strips bonded to concrete. \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Classification Category**} & \(F_{ub,predicted}/F_{ub,test}\) & **DPC Points** \\ \hline Extremely dangerous & \(\geq\)2.00 & 10 \\ Dangerous & 1.15–2.00 & 5 \\ Appropriate and safe & 0.85–1.15 & 0 \\ Conservative & 0.5–0.85 & 1 \\ Extremely conservative & \(<\)0.5 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The demerit points classification (DPC) scale. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **\textgreater{}2** & **1.15–2** & **0.85–1.15** & **0.5–0.85** & **\textless{}0.5** & **Total DPC** \\ \hline TR55/2000 ([PERSON] et al., 2018) & - & - & 6 & 36 & 49 & 134 \\ Fib Bulletin 14/2001 ([PERSON] et al., 2018) & - & 11 & 31 & 38 & 11 & 115 \\ JCI 2003 ([PERSON] et al., 2018) & - & 20 & 33 & 34 & 4 & 142 \\ SIA 166/2004 ([PERSON] et al., 2018) & - & 15 & 41 & 34 & 1 & 111 \\ CNR-DT200R1/13 ([PERSON] et al., 2018) & - & 20 & 37 & 29 & 5 & 139 \\ _Fib_ Bulletin 90/2019 ([PERSON] et al., 2018) & - & 21 & 40 & 29 & 1 & 136 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Classification of technical guidelines according to [PERSON] DPC scale; SRP composites bonded to concrete. Among the prediction guidelines concerning the SRP bonded to masonry, the lowest number of demerit points was obtained by the British standard TR55/20000 (28 points). Taking into account its strong tendency to lower the results (shown in Table 5), the Swiss Standard SIA 166/2004 should be assessed higher, despite the significantly higher number of demerit points (78 points).