## 5 Conclusions  
Collapse fragility of an electric cabinet in nuclear power plants with a tuned mass damper (TMD) under earthquake excitation is presented in this work. For this aim, the finite element model is developed and verified with the experimental test. The dynamic characteristics (such as natural frequencies and mode shapes) from the FEM are used to identify the damper. The time history analyses are carried out to determine the seismic performance of the equipment subjected to two specific records, which characterized for high-frequency and low-frequency ground motions. Finally, the fragility curves are developed to estimate the probabilistic failure of the structure.  
Two numeric models with and without a TMD system are considered to demonstrate the effectiveness of the vibration control system on the seismic performance of an electrical cabinet. The obtained results indicate that: (1) The TMD is an effective device to reduce the seismic response of the cabinet structure. This aspect is meaningful in controlling the structural response to protect the installed inside electrical devices; (2) More than 30% of the reduction of the response is found for the case with an installed control system.  
Two comparative earthquake groups with high- and low-frequency contents are used to investigate their influences on the response of the high-frequency electrical cabinet. From the observed results, it can be concluded that: (1) The structural response of the cabinet depends strongly on the frequency contents of the seismic input. More vulnerability is found for the high-frequency motions; (2) The defined AAF of the cabinet address that the HF motions are greater approximately three times compared to LF motions in both cases with and without TMD a TMD system.  
In order to evaluate the seismic vulnerability of the cabinet with a TMD subjected to high- and low-frequency earthquakes, the fragility analysis is developed by performing incremental dynamic analysis. The results show that the fragility functions under HF and LF motions are quite different, and it has the same trend for two models with and without a control system. Most vulnerability is found for the model without TMD system under HF earthquakes.  
In the present study, the frequency contents of the seismic input are considered without the consideration of the resonance effects. Hence, further works should be conducted to consolidate the influences of the seismic characteristics on the structural response of the cabinet.  
Conceptualization, T.-T.T. and S.C.; methodology, A.-T.C. and D.K.; validation, T.-T.T. and D.K.; writing--original draft preparation, A.-T.C. and T.-T.T.; writing--review and editing, T.-T.T. and S.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea grant number no 20171510101960.  
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20171510101960) and this study was conducted by research funds from Gwangju University in 2020.  
Figure 15: Probability of exceedance of the acceleration responses of the cabinet from the collapse threshold: (**a**) without TMD; (**b**) with TMD.