# Seismic Performance Assessments of RC Frame Structures Strengthened by External Precast Wall Panel
## 6 Concluding Remarks  
In this study, a strengthening method, using an externally anchored precast wall panel (EPCW), was proposed to overcome the disadvantages of the conventional infill wall seismic strengthening method. In order to assess the seismic performance of the proposed model, cyclic loading tests were conducted on the RC frame structures with non-seismic details, and the frame structures were strengthened by  
Figure 23: Load–displacement responses of idealized and simplified model: (**a**) Specimen FB; (**b**) Specimen FBC; (**c**) Specim FPB.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Cross Section**} & \multicolumn{2}{c}{**A\({}_{\text{lc}}\) (mm\({}^{\text{2}}\))**} & \multicolumn{2}{c}{**A\({}_{\text{ls}}\) (mm\({}^{\text{2}}\))**} \\ \cline{2-3}  & **Specimen FB, FBC** & **Specimen FPB** \\ \hline L1 & 22,500 & 3750 \\ \hline L2 & 39,375 & 18,750 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Cross-section of each element for simplified model.  
the EPCW method. The nonlinear finite element analysis models using the section aggregator, the fiber section analysis model and the modified LDLEM were also presented, to evaluate the structural behavior of the frame structures strengthened with precast walls. In addition, a simplified analysis model was proposed that was capable not only of reducing the number of longitudinal elements, but also of shortening the modeling and analysis time. The following conclusions can be obtained from this study:  
1. Specimen FC, an RC frame structure with non-seismic details, exhibited maximum loads of 54.6 and \(-\)51.7 kN in the positive and negative directions, respectively. The maximum loads of Specimens FBC and FB (strengthened with EPCW) were 240.1 and 238.9 kN in the positive direction, and \(-\)272.1 and \(-\)216.9 kN in the negative direction, showing a significant improvement in strength. Specim FPB, to which the scaled-down EPCW is applied in the form of a wing wall near the column, exhibited maximum loads of 150.9 and \(-\)158.1 kN in the positive and negative directions, respectively, showing a great increase in strength. Specim FPB also exhibited superior deformation capacity, as it showed stable behavior, even at 3.0% drift ratio;
2. The modeling of precast walls using LDLEM and section aggregator provided relatively accurate predictions on the overall behavior of the specimens and accurately evaluated the failure mode of the frame structures;
3. The test and analysis results confirmed that, compared to Specimen FBC, Specim FB has relatively superior deformation capacity, and suffers less damage to the column, resulting in more stable lateral behavior. When precast walls are connected to RC frame structures, the connection to the column may lead to large deformation and damage in the column. Therefore, it is advantageous to connect the precast wall only to the beam;
4. The simplified analysis model, which simplifies the number of longitudinal elements by dividing the wall into the end and center portions, showed very similar results to the analysis results of the idealized analysis model, which models all of the longitudinal reinforcements into longitudinal elements. Therefore, it is expected that our simplified analysis model can be practically applied to the evaluation of the behavior of buildings;
5. It should be noted that the observations drawn from this study are based on the experimental and analytical results of only four specimens; therefore, further study is still required.  
Investigation, [PERSON] and [PERSON]; supervision, K.S.K.; validation, [PERSON] and [PERSON]; writing--original draft, [PERSON]-[PERSON]; writing--review & editing, K.S.K. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Mid-Career Research Program through the National Research Foundation of Korea (NRF) (NRF-2019R1A2C2086388).  
The authors declare no conflict of interest.