충격시험을 이용한 강재 프레임 시편의 모드특성분석

소기환(Gi Hwan So),조성국(Sung Gook Cho),조양희(Yang Hee Joe),이용일(Yong Il Lee) 대한토목학회 2009 대한토목학회 학술대회 Vol.2009 No.10

산업시설 구조설계기준 - 수용구조물과 플랫폼

소기환(So, Gihwan),조성국(Cho, Sung Gook) 대한토목학회 2021 대한토목학회 학술대회 Vol.2021 No.10

화력발전플랜트의 내진설계방법 적용성 검토

소기환(So, Gihwan),조성국(Cho, Sung Gook),최송이(Choi, Song Yi) 대한토목학회 2022 대한토목학회 학술대회 Vol.2022 No.10

강재 코일 댐퍼의 배관시스템 진동제어 효과 분석을 위한 진동대시험

최송이,소기환,조성국 한국지진공학회 2022 한국지진공학회논문집 Vol.26 No.1

Many piping systems installed in the power plant are directly related to the safety and operation of the plant. Various dampers have been applied to the piping system to reduce the damage caused by earthquakes. In order to reduce the vibration of the piping system, this study developed a steel coil damper (SCD) with a straightforward structure but excellent damping performance. SCD reduces the vibration of the objective structure by hysteretic damping. The new SCD damper can be applied to high-temperature environments since it consists of steel members. The paper introduces a design method for the elastoplastic coil spring, which is the critical element of SCD. The practical applicability of the design procedure was validated by comparing the nonlinear force-displacement curves calculated by design equations with the results obtained from nonlinear finite element analysis and repeated loading test. It was found that the designed SCD’s have a damping ratio higher than 25%. In addition, this study performed a set of seismic tests using a shaking table with an existing piping system to verify the vibration control capacity on the piping system by SCD. Test results prove that the SCD can effectively control the displacement vibration of the piping system up to 80%.

비보강 강판콘크리트 전단벽의 횡하중 성능 및 강도특성에 대한 실험적 평가

조성국,소기환,김두기,권민호 한국지진공학회 2012 한국지진공학회논문집 Vol.16 No.5

최근 국내에서는 원자력발전소의 모듈화 공법에 적용하기 위하여 SC(steel plate concrete) 구조를 개발하는 연구를 진행하고 있다. 이 연구에서는 전단보강이 없는 비보강 SC 전단벽의 횡방향 내진성능 및 강성특성에 대하여 분석하기 위하여 전단벽 모형시편을 제작하고, 이를 대상으로 정적가력실험을 수행하였다. 실험 결과를 이용하여, 이 논문에서는 비보강 SC 구조의 횡력에 대한 파괴모드의 유형을 분석하고, 단면강도와 부재의 강성 특성을 검토하였다. 그리고 SC 구조용 설계기준에서 제시하는 단면의 강도 계산식과실험결과를 비교하였다. 연구결과, 비보강 SC 전단벽의 파괴 형태의 하나는 콘크리트와 강판의 부착 상실로 인한 휨전단파괴라는 사실을발견하였다. SC 구조 전단벽의 벽체 길이방향 거동은 파괴 시까지 벽체 외측의 강판이 내부 콘크리트를 구속하는 효과를 기대할 수 있으므로 연성능력이 향상되는 것이 확인되었다 Research on steel plate concrete (SC) structures for the modularization of nuclear power plants have been performed recently in Korea. In this study, the seismic capacity and stiffness characteristics of unstiffened SC shear walls under the effects of earthquakes were investigated through static pushover tests. Failure modes, sectional strength, and stiffness characteristics of SC structures under lateral loads were inspected by analyzing the experimental results. The strengths obtained by the experiments were also compared with those derived by the design code of the SC structures. One of the main failures of unstiffened SC shear walls was found to be the type of bending shear failure due to the debonding of the steel plate at the concrete interface. The ductility capacity of SC structures was also confirmed to be improved, which is considered to be a confining effect on steel plates in the longitudinal behavior of SC structures.

진동수영역해석법을 이용한 캐비닛내부응답스펙트럼 생성 기법

조성국,소기환 한국지진공학회 2020 한국지진공학회논문집 Vol.24 No.2

Seismic qualification of instruments and devices mounted on electrical cabinets in a nuclear power plant is performed in this study by means of the in-cabinet response spectrum (ICRS). A simple method and two rigorous methods are proposed in the EPRI NP-7146-SL guidelines for generating the ICRS. The simple method of EPRI can give unrealistic spectra that are excessively conservative in many cases. In the past, the time domain analysis (TDA) methods have been mostly used to analyze a structure. However, the TDA requires the generation of an artificial earthquake input motion compatible to the target response spectrum. The process of generating an artificial earthquake may involve a great deal of uncertainty. In addition, many time history analyses should be performed to increase the accuracy of the results. This study developed a numerical analysis program for generating the ICRS by frequency domain analysis (FDA) method. The developed program was validated by the numerical study. The ICRS calculated by FDA thoroughly matched with those obtained from TDA. This study then confirms that the method it proposes can simply and efficiently generate the ICRS compared to the time domain method.

가진기를 이용한 강제진동시험에 의한 전기 캐비닛의 실험적 모드특성 분석

조성국,소기환 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.6

원자력발전소(이하, 원전)에 설치되는 안전관련 전기기기들의 합리적인 내진검증을 위해서는 사전에 정확한 동특성분석이 필요하다. 이 연구에서는 원전에 설치되는 전기기기 캐비닛 구조를 대상으로 입력 진동의 수준에 따른 모드특성의 변화를 평가하였다. 이를 위해, 실제 전기기기 캐비닛을 시편으로 선정하고 가진 시험기를 이용하여 입력진동에너지의 크기를 변화시켜 가면서 진동시험을 수행하였다. 시험은 캐비닛의 문짝을 부착한 경우와 탈거한 경우로 구분하여 수행하였다. 진동시험을 통하여 계측된 시편의 가속도응답신호와 입력운동신호로부터 진동의 크기에 따라 진동수응답함수를 작성하였다. 다항식회귀분석기법을 이용한 모드분석기법으로 시편의 진동수응답함수를 분석하여 모드특성을 추출하고, 진동수준에 따른 시편의 동특성 변화를 검토하였다. 연구결과, 대상 기기는 입력진동의 크기가 증가할수록 모드진동수와 모드감쇠비가 비선형적으로 변화하는 것을 확인하였다. 문짝이 부착된 경우에는 문짝이 탈거된 경우에 비하여 캐비닛의 모드감쇠가 증가한다. Accurate modal identification analysis is required to reasonably perform a seismic qualification of safety-related electric equipment installed in nuclear power plants (NPPs). This study evaluates a variation of the modal properties of an electric equipment cabinet structure in NPPs according to the excitation levels. For the study, an actual electric equipment cabinet was selected as a specimen and was dynamically tested by using a portable exciter in accordance with the level of input vibration energy. Tests were classified into two sets: with-door cases, and without-door cases. Frequency response functions were computed from the signals of the acceleration responses and input motions measured from the vibration tests. A polynomial curve fitting algorithm was used to extract the modal properties from the frequency response functions. This study reviews the variation of the modal properties according to the variation of the excitation levels. The results of the study show that the modal frequencies and the modal dampings of the object specimen varies nonlinearly according to the excitation level of the test motion. Attaching the door increases the modal damping of the cabinet.

진동시험을 통한 강판콘크리트(SC) 전단벽의 저응력수준에서의 구조 감쇠비 규명

조성국,소기환,김두기,한상묵,Cho, Sung Gook,So, Gihwan,Kim, Doo Kie,Han, Sang Mook 대한토목학회 2015 대한토목학회논문집 Vol.35 No.2

SC (steel plate concrete)구조는 새로운 구조형식으로서 SC구조물의 내진설계에 적용할 수 있는 감쇠비의 규명이 필요하다. 이 연구에서는 실험적 방법을 통해 SC구조의 감쇠비를 분석하였다. 연구를 위하여 SC 전단벽 시편을 제작하고, 대형 진동대를 이용하여 진동시험을 수행하였다. 시험에서 계측한 가속도응답신호는 전달함수로 변환한 후 동적실험모드분석기법을 적용하여 분석하였다. 구조물의 감쇠비는 입력운동의 수준에 따라 달라질 수 있으며, 이 연구의 실험에서 적용한 입력운동의 수준은 시편의 항복강도의 절반보다 낮은 수준으로서 여기서 분석된 구조감쇠비는 약 4%정도이다. 이 연구결과를 고려하여 SC구조물의 운전기준지진에 대한 내진설계에는 4% 감쇠비를 적용할 수 있을 것으로 판단된다. Steel plate concrete (SC) structure has been developed as a new structural type. Rational damping value shall be determined for the seismic design of SC structure. This study evaluated damping ratio of SC structure through experiments. For the study, a SC shear wall specimen was constructed and dynamically tested on the shaking table. Acceleration time history responses measured from testing were converted to the transfer functions and analyzed by using experimental modal analysis technique. The structural damping ratio of the specimen was identified as 4% to critical. Considering the shaking table test was performed at the excitation level corresponding to the low stress level of the specimen, 4% could be suggested as a structural damping for design of SC structure for operating basis earthquake.

횡방향 가력실험 및 충격실험을 통한 강판콘크리트(SC) 전단벽의 감쇠비 평가

조성국,소기환,박웅기 한국지진공학회 2013 한국지진공학회논문집 Vol.17 No.2

Steel plate concrete (SC) composite structure is now being recognized as a promising technology applicable to nuclear power plants as it is faster and suitable for modular construction. It is required to identify its dynamic characteristics prior to perform the seismic design of the SC structure. Particularly, the damping ratio of the structure is one of the critical design factors to control the dynamic response of structure. This paper compares the criteria for the damping ratios of each type of structures which are prescribed in the regulatory guide for the nuclear power plant. In order to identify the damping ratio of SC shear wall, this study made SC wall specimens and conducted experiments by cyclic lateral load tests and vibration tests with impact hammer. During the lateral loading test, SC wall specimens exhibited large ductile capacities with increasing amplitude of loading due to the confinement effects by the steel plate and the damping ratios increased until failure. The experimental results show that the damping ratios increased from about 6% to about 20% by increasing the load from the safe shutdown earthquake level to the ultimate strength level.

면진테이블을 적용한 중요 통신설비의 내진대책

조성국,박웅기,소기환 한국재난정보학회 2014 한국재난정보학회 학술대회 Vol.2014 No.1