This study performed the seismic response analysis of an LNG storage tank supported by a disconnected piled raft foundation (DPRF) with a load transfer platform (LTP). For this purpose, a precise analytical model with simultaneous consideration of Fluid-Structure Interaction (FSI) and Soil-Structure Interaction (SSI) was used. The effect of the LTP characteristics (thickness, stiffness) of the DPRF system on the seismic response of the superstructure (inner and outer tanks) and piles was analyzed. The analytical results were compared with the response of the piled raft foundation (PRF) system. The following conclusions can be drawn from the numerical results: (1) The DPRF system has a smaller bending moment and axial force at the head of the pile than the PRF system, even if the thickness and stiffness of the LTP change; (2) The DPRF system has a slight stiffness of the LTP and the superstructure member force can increase with increasing thickness. This is because as the stiffness of the LTP decreases and the thickness increases, the natural frequency of the LTP becomes closer to the natural frequency of the superstructure, which may affect the response of the superstructure. Therefore, when applying the DPRF system, it is recommended that the sensitivity analysis of the seismic response to the thickness and stiffness of the LTP must be performed.

1. 서 론
2. 유체-구조물-지반 상호작용을 고려한 지진응답해석
    2.1 유체-구조물 상호작용 해석(FSI)
    2.2 지반-구조물 상호작용 해석(SSI)
3. 해석 사례
    3.1 예제구조물 및 지반 특성
    3.2 입력지진
    3.3 자유장해석
    3.4 하중전달플랫폼(LTP)
    3.5 지진응답해석 모델
4. 해석 결과
    4.1 기초 및 상부 구조물의 전달함수 비교
        4.2 상부 구조물 및 말뚝의 부재력 비교
5. 결 론

• 손일민(전남대학교 일반대학원 건축토목공학과 박사) | Son, Il-Min (Ph. D, Department of Architecture and Civil Engineering, Graduate School, Chonnam National University)
• 김재민(전남대학교, 토목공학과 교수) | Kim, Jae-Min (Professor, Department of Civil Engineering, Chonnam National University) Corresponding author