# Seismic Performance Assessments of RC Frame Structures Strengthened by External Precast Wall Panel
## 5 Verifications of the Analysis Model  
### Overall Cyclic Responses and Cumulative Energy Dissipation Capacities  
Figure 9 compares the test and analysis results obtained using the modified LDLEM. Table 2 summarizes the maximum strengths in the positive and negative directions in the test and analysis results. The strength ratios of the analysis/test results obtained from Specim FB were 0.97 and 1.02 in the positive and negative directions, respectively. These strength ratios obtained from Specim FBC were 0.96 and 0.81 in the positive and negative directions, respectively. These results show that that there was a tendency to underestimate the strength of the specimen in the negative direction, but the overall behavior was similar. These strength ratios obtained from Specim FPB were 1.11 and 1.02 in the positive and negative directions, respectively. Therefore, it was found that the analytical method applied with the modified LDLEM accurately evaluated the overall behavior of specimens strengthened with precast walls.  
Figure 14 compares the test and analysis results regarding the secant stiffness of the specimens normalized by the ratio to the initial stiffness. The analysis results were found to accurately evaluate the secant stiffness degradation characteristics, indicating accurate predictions of the strength reduction characteristics according to each loading step.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Cross Section**} & \multicolumn{2}{c}{**A\({}_{\text{lc}}\) or A\({}_{\text{dc}}\) (mm\({}^{2}\))**} & \multicolumn{2}{c}{**A\({}_{\text{ls}}\) (mm\({}^{2}\))**} \\ \cline{2-3}  & **Specimen FB, FBC** & **Specimen FPB** \\ \hline L1 & 7500 & 3750 \\ \hline L2 & 13,125 & 7500 \\ \hline L3 & 2812.5 & 1875 \\ \hline D1 & 8049.4 & 4500 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Cross-section of each element for idealized analysis model.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Specimen**} & \multicolumn{3}{c}{**Strength(kN)**} \\ \cline{2-4}  & **Analysis** & **Test** & **Analysis/Test** \\ \hline \multirow{2}{*}{FB} & 232.9 & 238.9 & 0.97 \\ \cline{2-4}  & \(-\)220.6 & \(-\)216.9 & 1.02 \\ \hline \multirow{2}{*}{FBC} & 229.6 & 240.1 & 0.96 \\ \cline{2-4}  & \(-\)219.9 & \(-\)272.1 & 0.81 \\ \hline \multirow{2}{*}{FPB} & 167.4 & 150.9 & 1.11 \\ \cline{2-4}  & \(-\)161.1 & \(-\)158.1 & 1.02 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Summary of test and analysis result.  
In order for the system to exert sufficient seismic performance, the structure must, after yielding, be able to dissipate sufficient energy. Therefore, cumulative energy dissipation serves as an important indicator related to the seismic performance of structures [4]. Figure 15 compares the amount of cumulative energy dissipation of specimens subjected to cyclic loads, and that of their energy dissipation calculated based on the analysis. In this study, the amount of cumulative energy dissipation was defined as the enclosed area of the load-displacement hysteresis loop. The analysis model provided relatively accurate evaluations of the energy dissipation capacity under cyclic loading. However, the difference between the test and analysis results regarding the energy dissipation capacity of Specim FBC was relatively larger than that of the other test specimens. This is because a sudden increase in strength occurred in the negative direction during the test of Specim FBC, as shown in Figure 9b.  
Figure 14: Measured and estimated normalized stiffness: (**a**) Specim FB; (**b**) Specim FBC; (**c**) Specim FPB.