## 5 Conclusions  
A statistical analysis was conducted on the number of ground motions used to generate seismic fragility curves, which are widely used in damage assessments of structures affected by earthquakes. Using 400 ground motions, the study employed LHS, a sampling method commonly used in engineering experiments, to select various sets of ground motions. Seismic fragility curves were then generated for two example structures (a 6-story and a 13-story steel moment frame structure), using inter-story drift as the performance criterion for three performance levels.  
The six-story structure, which has lower degrees of freedom, exhibited relatively small differences between the reference values for the median and log-standard deviation, whereas the 13-story structure, with higher degrees of freedom, exhibited relatively larger differences. However, when 50 or more ground motions were considered, the results for both example structures were similar. When comparing the median values, the difference from the reference values was less than 0.26% for the six-story structure and less than 0.36% for the 13-story structure. For the log-standard deviation, the difference was less than 0.73% and 0.59%, respectively, exhibiting minimal differences from the reference values, regardless of the degrees of freedom of the structures.  
This study reveals that the ground motions considered when deriving seismic fragility curves based on inter-story drift are directly related to the structural response of the target facility. If the fragility curves are generated using relatively few ground motions, the uncertainty in the fragility curve variables increases, potentially distorting the results. Distorted results likely lead to inaccuracies in further analyses, such as seismic performance evaluations or damage cost estimations when using the fragility curve results. Therefore, considering an appropriate selection of ground motions and an adequate number of ground motions is important when generating seismic fragility curves. Finally, by increasing the number of ground motions, the amount of data available for deriving the input variables of the fragility curves also increases. This increase in data helps reduce uncertainty due to data limitations, improving the reliability of the fragility curve input variables.  
Finally, this study has the limitation that it requires a high computational cost to provide more practical application through nonlinear time history analysis for various structural models. Also, the impact of the design characteristics and material properties of the two steel frame examples on seismic response and fragility assessment cannot be neglected. However, this study can provide information on the relationship between the number of input ground motions and seismic fragility curves, and it may be helpful to consider an appropriate number of ground motions for seismic fragility analysis.  
Conceptualization: S.P. and D.S.; formal analysis: S.P. and K.J.; funding acquisition: D.S. and J.K.; investigation: S.P. and J.K.; methodology: S.P.; project administration: D.S.; validation: K.J.; writing--original draft: S.P. and D.S.; writing--review and editing: K.J. and J.K. All authors have read and agreed to the published version of the manuscript.  
This study was supported by the Ministry of Land, Infrastructure and Transport (MOLIT) (Project Number: KICT-20240043-001).  
Not applicable.  
The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding authors.  
**Conflicts of Interest:** The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.