Seismic fragility curves present the conditional probability of damage to target structures due to external seismic load and are widely used in various ways. When constructing such a seismic fragility curve, it is essential to consider various types and numbers of ground motions. In general, the earthquake occurrence characteristics of an area where the target structure of the seismic fragility curve exists are analyzed, and based on this, appropriate ground motions are selected to derive the seismic fragility curve. If the number of selected ground motions is large, the diversity of ground motions is considered, but a large amount of computational time is required. Conversely, if the number of ground motions is too small, the diversity of ground motions cannot be considered, which may distort the seismic fragility curve. Therefore, this study analyzed the relationship between the number of ground motions considered when deriving the seismic fragility curve and the parameters of the seismic fragility curve. Using two example structures, numerical analysis was performed by selecting a random number of ground motions from a total of two hundred, and a seismic fragility curve was derived based on the results. Analysis of the relationship of the parameter of the seismic fragility curve and the number of selected ground motions was performed. As the number of ground motions considered increases, uncertainty in ground motion selection decreases, and when deriving seismic fragility curves considering the same number of ground motions, uncertainty increases relatively as the degree of freedom of the target structure increases. However, considering a relatively large number of ground motions, uncertainty appeared insignificant regardless of increased degrees of freedom. Finally, it is possible that the increase in the number of ground motions could lower the epistemic uncertainty and thus improve the reliability of the results.

1. 서 론
2. 입력지진파의 종류 및 특성
3. 지진취약도 이론
4. 입력지진파의 수와 지진취약도의 관계 분석
    4.1 예제 시설물: 6층 상업 시설물
    4.2 예제 시설물: 13층 상업 시설물
5. 결 론
/ 감사의 글 /
/ REFERENCES /

• 박상기(한국건설기술연구원 구조연구본부 수석연구원) | Park Sangki (Senior Researcher, Department of Structural Engineering Research, Korea Institute of Civil Engineering and Building Technology) Corresponding author
• 박기태(한국건설기술연구원 구조연구본부 선임연구위원) | Park Ki-Tae (Senior Research Fellow, Department of Structural Engineering Research, Korea Institute of Civil Engineering and Building Technology)
• 김재환(한국건설기술연구원 구조연구본부 수석연구원) | Kim Jaehwan (Senior Researcher, Department of Structural Engineering Research, Korea Institute of Civil Engineering and Building Technology)
• 정규산(한국건설기술연구원 구조연구본부 수석연구원) | Jung Kyu-San (Senior Researcher, Department of Structural Engineering Research, Korea Institute of Civil Engineering and Building Technology)
• 서동우(한국건설기술연구원 구조연구본부 연구위원) | 서동우서동우