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.

지진취약도를 산정하기 위해서는 목표 부지의 특성을 제대로 표현할 수 있는 입력 지진파의 산정이 중요하다. 본 논문에서는 국내 외 강진 및 중‧약진 지역에서의 입력 지진파에 대한 단자유도 모델의 지진취약도를 분석하였다. 분석을 위한 첫 번째 단계로, 국외 강 진 기록 중 근/원거리에서 측정한 2개의 입력 지진파 세트와 국내 중·약진 지역 특성에 적합한 입력 지진파 2개의 세트, 총 4개의 입력 지진파 세트를 선정하였다. 대상 구조물로는 3가지 고유주기에 대한 비선형 단자유도 모델을 적용하였고, 취약도 분석을 위해 증분동 적해석을 이용하였다. 또한, 4가지 손상 상태를 정의하고, 손상 상태 각각에 대해 4가지 입력 지진파 세트의 고유주기별 지진취약도 결과를 제시하였다.

Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in companion paper and the latter in this paper. In order to investigate the effect of an input earthquake motion on the permanent deformation, three bins of spectral matched real earthquake records with different magnitude, regions, epicentral distance are constructed. Parametric study was performed using the verified RHA through the companion paper for each earthquake records in the bins. The most influential parameter affecting permanent displacement is magnitude. The other parameters describing earthquake motion are not significant enough to increase permanent displacement of the inverted T-type wall except for energy related parameters(AI, CI, SEI).

대부분의 대공간구조물은 극장, 스타디움, 체육관 등 공공성을 가지게 되어 내진안전성에 있어서 중요성이 많이 인식되고 있다. 그러나 구조형식 및 형상에 관하여 다양성을 가지고 있는 대공간구조물이 동적하중인 지진하중을 받을 때 나타나는 구조물의 거동은 파악하기 힘들다. 본 논문에서는 대공간구조의 주 구조요소인 아치구조물에 대하여 고유진동모드를 검토하였고 모의지진파를 입력하여 지진거동특성을 분석한 결과로서 아치구조물은 설계가속도스펙트럼의 크기보다 장주기 성분에 더 많은 영향을 받는다는 것을 파악하였다.