## 6 Comparison of the Pseudo-Dynamic Test and Nonlinear Dynamic Analysis Results
### Nonlinear Dynamic Analysis Results before and after Seismic Strengthening  
Nonlinear dynamic analysis was conducted based on the seismic strengthening design results shown in Section 7.1 and the analysis models of the target building before and after seismic strengthening. Consequently, for the unreinforced building, shear cracks occurred in the column member at 2.25 s (displacement: 4.7 mm) under 200 cm/s\({}^{2}\). A maximum seismic response strength of 3584.2 kN (displacement: 49.1 mm) occurred at 3.3 s, and finally the unreinforced building collapsed due to shear cracks at 3.3 s when the maximum seismic response was observed. In the case of the target building reinforced with CCSS, shear cracks occurred in the column member at 2.5 s (6.8 mm) under 200 cm/s\({}^{2}\). No additional maximum response, however, occurred after showing the maximum seismic response at 6.8 s (13.6 mm), resulting in small seismic damage. Figure 22 shows the load-displacement curves of the unreinforced and CCSS-reinforced buildings on the first floor under 200 cm/s\({}^{2}\). Figure 23 shows the time-displacement history curves under the same ground motion. Table 10 shows the maximum response strength, maximum response displacement, and displacement ratio, which are important elements for seismic performance assessment, among the analysis results for the CCSS-reinforced building and unreinforced building under 200 cm/s\({}^{2}\). Figure 22: Seismic response load–displacement of non-strengthened buildings and buildings strengthened by CCSS (1F). \begin{table}
\begin{tabular}{c c c c c} \hline
**CCSS Strength** **[kN]** & **Targeted** **SEISMIC Performance** & **Floor** & **Required** **CCSS Strength** **CV9 (kN)** & **Number of Required** **CCSS Systems** **[EA]** & **Number of Applied** **CCSS Systems** **CESS Systems** **Strengthening** **[EA]** \\ \hline  & & 1 & 3173.5 & 5.3 & 6 \\ \cline{3-5}
600 & 0.52 & 2 & 2644.6 & 4.4 & 6 \\ \cline{3-5}  & & 3 & 1643.4 & 2.7 & 4 \\ \hline \end{tabular}  
* CCSS strength used in a single frame for seismic strengthening was assumed to be 600 kN based on test and analysis results presented in Sections 3–6.  
\end{table} 
Table 9: Calculated magnitude of the seismic strengthening of CCSS seismic systems. According to the above figures and table, compared to the unreinforced building, the CCSS-reinforced building was suppressed by approximately 0.28 times on the first floor, 0.47 times on the second floor, and 0.66 times on the third floor under the input ground motion of 200 cm/s\({}^{2}\). This confirmed the validity of the seismic strengthening design method and the proposed CCSS method. Figure 24 show the ductility ratios (\(\mu_{s}\)) of the column members on each floor with respect to shear deformation in the unreinforced building and CCSS-reinforced building. The ductility ratio in the figures was defined as the ratio of the maximum shear deformation (\(\delta_{max}\)) to the displacement at the time of shear cracking (\(\delta_{c}\)), which was shown in Equation (13); i.e., \(\mu_{s}=\delta_{max}/\delta_{c}\). \(\mu_{s}=1\) indicates the time of shear cracking, and \(\mu_{s}=5\) denotes the time of shear failure. In addition, I, II, III, IV, and V in the figures represent the seismic damage classes described in JBDPA [22] and Maeda, Nakano, and Lee [23].