## 8 Conclusions  
This study proposed a CFT CCSS, which is a new concept that can improve and supplement the vulnerability of existing seismic strengthening methods. The pseudo-dynamic test was conducted on two-story framework specimens based on an existing reinforced concrete (R/C) building with non-seismic features to verify the seismic strengthening effect of applying the CCSS to existing R/C buildings. Based on the pseudo-dynamic test results, restoration force characteristics were proposed for the nonlinear dynamic analysis of the CCSS-reinforced building. Nonlinear dynamic analysis was conducted based on the proposed restoration forces, and the results were compared with the pseudo-dynamic test results. Finally, for the commercialization of the CCSS, nonlinear dynamic analysis was conducted on the existing R/C building with non-seismic features reinforced with the CCSS. The seismic strengthening effect was comprehensively verified by examining the seismic response load, displacement characteristics, and the degree of damage to members before and after seismic strengthening. The study results can be summarized as follows. 1. The unreinforced pseudo-dynamic test specimen showed a maximum seismic displacement of 70.5 mm (strength: 272.5 kN) at 3.43 s for the DBE (Hachinohe (EW))  
Figure 24: Distribution of the ductility ratios of columns with respect to the shear deformation of existing non-strengthened buildings and CCSS-strengthened buildings based on the nonlinear dynamic analysis. Note: Damage classes are defined by JBDPA [22] and Maeda, Nakano, and Lee [23]. seismic wave with a magnitude of 200 cm/s\({}^{2}\), and shear failure occurred. This shows that R/C buildings with non-seismic features are highly susceptible to serious seismic damage under a DBE ground motion of 200 cm/s\({}^{2}\). This is judged to be important information for securing the seismic safety of R/C buildings without seismic design, i.e., seismic reinforcement. 2. In the case of the CCSS-reinforced framework specimen, the maximum displacement was 10.6 mm (strength: 488.6 kN) under a DBE ground motion of 200 cm/s\({}^{2}\), and minor flexural and shear cracks were observed. Under an MCE of 300 cm/s\({}^{2}\), the maximum seismic response displacement was 20.4 mm (strength: 708.1 kN), and small flexural and shear cracks were observed. Under a seismic wave of 400 cm/s\({}^{2}\), which represents a large earthquake, the maximum displacement was 35.2 mm (strength: 864.9 kN), and the degree of seismic damage was moderate. 3. The CCSS is judged to be a typical seismic strengthening method considering that the maximum strength increased by approximately 1.79 times under the seismic wave of 200 cm/s\({}^{2}\), 2.6 times under 300 cm/s\({}^{2}\), and 3.17 times under 400 cm/s\({}^{2}\) compared to that of the specimen with non-seismic features (PD-FR), which showed shear failure under the Hachinohe (EW) 200 cm/s\({}^{2}\) seismic wave. For the specimen reinforced with the CCSS method, the seismic displacement was suppressed by approximately 84% under the same seismic wave, i.e., 200 cm/s\({}^{2}\), compared to the control specimen. This verified the seismic safety of the developed CCSS method. 4. Based on the pseudo-dynamic test results of CCSS, the restoration force characteristics of the beams, columns, and reinforcement (CCSS) were proposed for the nonlinear dynamic analysis of the two-story framework specimen reinforced with the CCSS. Based on the proposed restoration forces, nonlinear dynamic analysis was conducted on the pseudo-dynamic test specimens, and the results were compared with the pseudo-dynamic test results. The results were found to be similar, and the average difference in the seismic response load and displacement was less than 10%. This indicates that the seismic strengthening effect of the CCSS can be effectively evaluated using nonlinear dynamic analysis based on the nonlinear analysis model and the method developed in this study. 5.