## 5 Conclusions  
In this study, a seismic retrofitting method using a WCFST system was proposed in order to improve the seismic performance of an RC moment-resisting frame without seismic details. One non-seismically designed reinforced concrete frame specimen and one specimen retrofitted with the WCFST system were subjected to cyclic lateral loading tests. Crack patterns, failure modes, maximum load, effective stiffness, and energy dissipation were evaluated. The conclusions from this study are as follows:  
1. All of the specimens showed initial cracking at the bottom of the column at a drift ratio of 1%; the number and width of cracks at the beam-column joint and column increased as the load increased. As the drift ratio increased, the width of the shear cracks on the column increased, concrete spalling occurred, and failure of the specimens was observed at a drift ratio of 2.5%. For the NRC specimen without seismic details, the loading experiment was terminated after shear cracks were observed in the column, as the crack in the column and the overall number of cracks rapidly increased and the lateral reinforcement of the left column buckled. In the case of the WCFST specimen retrofitted according to the proposed method, the increase in shear crack width was not significant (unlike the case of the NRC specimen) and some concrete spalling was observed only at the bottom of the column. No deformation or elimination of the CFST frame was evident when the experiment was terminated. Figure 13: Cumulative energy dissipation from the specimens. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Drift Ratio (\%)**} & \multicolumn{2}{c}{**Cumulative Energy Dissipation (kN-mm)**} & \multirow{2}{*}{**Cumulative Energy Dissipation Ratio**} \\ \cline{2-2}  & **NRC** & **WCFST** & **of WCFST to NRC** \\ \hline
0.1 & - & - & - \\
0.25 & 246.26 & 453.45 & 1.84 \\
0.5 & 962.21 & 1883.78 & 1.96 \\
0.75 & 2176.84 & 4641.06 & 2.13 \\
1.0 & 3956.35 & 8805.30 & 2.23 \\
1.5 & 8147.52 & 18,723.15 & 2.30 \\
2.0 & 13,864.04 & 33,974.65 & 2.45 \\
2.5 & - & 55,261.46 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison of cumulative energy dissipation according to the drift ratio. 2. The maximum loads of the NRC and WCFST specimens were 332 kN and 1013.32 kN in the positive direction, and \(-\)314.2 kN and \(-\)940.5 kN in the negative direction, respectively. When the proposed seismic retrofitting method was applied, the ability to resist lateral forces increased by about three times when compared with the existing reinforced concrete structure. 3. Unlike the NRC specimen, where the strain at the end of the beams did not increase significantly despite the increase in drift ratio, the strain of the WCFST specimen continuously increased from a drift ratio of 0.75% until failure of the specimen occurred. Such a result confirmed that the stress of the test specimen retrofitted by the WCFST system was not concentrated on the columns, but distributed throughout the specimen. When the concrete strain values of the column lateral reinforcement were examined, the NRC specimen exceeded the ultimate compressive strain of the concrete after a drift ratio of 1% was reached. The longitudinal and transverse reinforcement for both specimens yielded at drift ratios of 1.5% and 2%, respectively. In the NRC specimen, the strain increased rapidly after yield of the reinforcement and, thus, the experiment was terminated. However, in the case of the WCFST specimen, the strain gradually increased to the drift ratio at which final failure occurred after yield of the reinforcement. This observation indicated that the seismic retrofitting method using the WCFST system can distribute stress concentrated on the column evenly on the test specimen, and can increase the lateral resistance capacity of the column. 4. The test specimen with the WCFST system was confirmed to have an effective stiffness two times greater than that of the NRC specimen without seismic details.