Safety-related cabinets and their electrical parts, such as relays and switches in nuclear power plants, should maintain continuous functioning, as well as structural safety according to the nuclear regulatory guidelines. Generally, an electrical part is qualified if its functioning is maintained without abnormality during excitement by motion compatible with the test response spectrum, which is larger than its in-cabinet response spectrum (ICRS). ICRS can be determined by shake-table test or dynamic analysis. Since existing cabinets in use can hardly be stopped and moved, dynamic analysis is preferred over shake-table test in determining ICRS. The simple method, suggested by the Electric Power Research Institute (EPRI) to determine ICRS, yields conservative or non-conservative results from time to time. In order to determine that the ICRS is better than EPRI method in a simple way, Ritz method considering global and local plate behaviors was suggested by Gupta et al. In this paper, the Ritz method is modified in order to consider the rocking and frame behaviors simultaneously, and it is applied to a simple numerical example for verification. ICRS is determined by Ritz method and compared with the results by finite element method (FEM). Based on this numerical example, recommendations for using Ritz method are suggested.

A B S T R A C T
1. 서 론
2. 캐비닛내부응답스펙트럼(ICRS)
3. 캐비닛에 대한 리츠방법 적용
    3.1 일반화된 운동방정식
    3.2 고유진동수
4. 해석예제
    4.1 제원 및 경계조건
    4.2 리츠방법
    4.3 감쇠의 적용
    4.4 지진하중에 대한 응답
    4.5 유한요소해석 및 비교
5. 결 론
REFERENCES

• 김기현(국민대학교 건설시스템공학과) | Kim Ki Hyun (Dep. of Civil Engineering, Kookmin University)
• 홍기증(국민대학교 건설시스템공학과) | Hong Kee-Jeung (Dep. of Civil Engineering, Kookmin University) Corresponding author
• 조성국(이노스기술(주)) | Cho Sung Gook (Innose Tech)
• 박웅기(이노스기술(주) 과장) | Park Woong Ki (Innose Tech, Representative Director)