지진격리된 원전배관의 지진취약도 분석

전법규,최형석,함대기,김남식 한국지진공학회 2015 한국지진공학회논문집 Vol.19 No.1

Base isolation is considered as a seismic protective system in the design of next generation Nuclear Power Plants (NPPs). If seismic isolation devices are installed in nuclear power plants then the safety under a seismic load of the power plant may be improved. However, with respect to some equipment, seismic risk may increase because displacement may become greater than before the installation of a seismic isolation device. Therefore, it is estimated to be necessary to select equipment in which the seismic risk increases due to an increase in the displacement by the installation of a seismic isolation device, and to perform research on the seismic performance of each piece of equipment. In this study, modified NRC-BNL benchmark models were used for seismic analysis. The numerical models include representations of isolation devices. In order to validate the numerical piping system model and to define the failure mode, a quasi-static loading test was conducted on the piping components before the analysis procedures. The fragility analysis was performed by using the results of the inelastic seismic response analysis. Inelastic seismic response analysis was carried out by using the shell finite element model of a piping system considering internal pressure. The implicit method was used for the direct integration time history analysis. In addition, the collapse load point was used for the failure mode for the fragility analysis.

다중 적층형 금속 벨로우즈 신축관이음의 내진성능 시험

전법규,김성완,윤다운,주부석,유진석 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.4

Pipelines are representative infrastructure facilities. Damage to pipelines caused by earthquakes is highly to cause serious damage for city. Therefore, pipeline need to be protected from earthquakes. But large relative displacements exceeding the allowable displacement of pipe can be caused by earthquakes. This seismic behaviors could causes damage to the joint of the pipe. The seismic performance of the pipe can be improved by applying a seismic separation joint to a location where excessive deformation of the pipe may occur. The multi-ply metal bellows has good durability against low-cycle fatigue loads such as earthquakes. Therefore multi-ply metal bellows could be used as seismic separation joint of pipes. In this study, Experimental study was performed for multi-ply metal bellows which is the one of seismic separation joint. Monotonic and cyclic loading tests were performed on two types of multi-ply metal bellows and limit state was estimated. The difference of leakage displacement in the monotoinc loading tests are less than 2%. However, the leakage displacement of the cyclic loading tests showed a difference of more than 12%. As a result, more layers of bellows could improve the performance for cyclic loading of multi-ply metal bellows. 배관시스템은 대표적인 사회기반시설이다. 지진으로 인한 배관 손상은 심각한 피해를 초래할 수 있으므로 배관시스템은 지진으로부터 반드시 보호되어야 할 필요가 있다. 지진은 설계기준을 초과하는 상대변위를 동반할 수 있다. 이러한 지진의거동은 배관 이음부에 손상을 줄 수 있다. 배관시스템에서 과도한 변형이 발생할 수 있는 위치에 지진분리이음을 적용하면 내진성능을 향상시킬 수 있다. 적층형 금속 벨로우즈는 지진과 같은 저주기 피로 하중에 대한 내구성이 우수하다. 따라서 다중 적층형 금속 벨로우즈는 파이프의 면진 이음새로 사용할 수 있을 것으로 판단된다. 본 연구에서는 지진분리이음의 하나인 다중 적층형 금속 벨로우즈에 대한 실험적 연구를 수행하였다. 2종류의 다중 적층형 벨로우즈 신축관이음에 대하여 단조하중 및 반복하중재하시험을 수행하고 손상모드와 한계상태를 추정하였다. 그리고 단조재하시험과 반복재하시험의 결과를 비교 분석하였다.

Seismic behavior of simplified electrical cabinet model considering cast-in-place anchor in uncracked and cracked concretes

전법규,김성완,장성진,박동욱,이홍표 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.11

In the case of nuclear power plants near end of their design life, a reassessment of the performance of safetyrelated equipment may be necessary to determine whether to shut down or extend the operation of the power plant. Therefore, it is necessary to evaluate the level of performance decline due to degradation. Electrical cabinets, including MCC and switchgear, are representative safety-related equipment. Several studies have assessed the degradation and seismic performance of nuclear power plant equipment. Most of those researches are limited to individual components due to the size of safety-related equipment and test equipment. However, only a few studies assessed the degradation performance of electrical cabinets. The equipment of various nuclear power plants is anchored to concrete foundations, and crack in concrete foundations is one of the most representative of degradation that could be visually confirmed. However, it is difficult to find a study for analysis through testing the effect of cracks in concrete foundations on the response of electrical cabinet internal equipment fixed by anchors. In this study, using a simple cabinet model considering cast-in-place anchor in uncracked and cracked concretes, a tri-axial shaking table tests were performed and the seismic behavior were observed.

Base isolation performance of a cone-type friction pendulum bearing system

전법규,장성진,김성완,김남식 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.2

A CFPBS (Cone-type Friction Pendulum Bearing System) was developed to control the acceleration delivered to a structure to prevent the damage and degradation of critical communication equipment during earthquakes. This study evaluated the isolation performance of the CFPBS by numerical analysis. The CFPBS was manufactured in the shape of a cone differenced with the existing FPS (Friction Pendulum System), and a pattern was engraved on the friction surface. The natural frequencies of the CFPBS were evaluated from a free-vibration test with a seismic isolator system consisting of 4 CFPBS. To confirm the earthquake-resistant performance, a numerical analysis program was prepared using the equation of the CFPBS induced from the equations of motion. The equation reported by Tsai for the rollingtype seismic isolation bearings was proposed to design the equation of the CFPBS. Artificial seismic waves that satisfy the maximum earthquake scale of the Korean Building Code-Structural (KBC-2005) were created and verified to review the earthquake-resistant performance of the CFPBS by numerical analysis. The superstructural mass of the CFPBS and the skew angle of friction surface were considered for numerical analysis with El Centro NS, Kobe NS and artificial seismic waves. The CFPBS isolation performance evaluation was based on the numerical analysis results, and comparative analysis was performed between the results from numerical analysis and simplified theoretical equation under the same conditions. The validity of numerical analysis was verified from the shaking table test.

EZ-LOK 조인트가 적용된 주철 매립 상수도관의 지진 안전성 평가

전법규,김재봉,윤다운,안성우 한국복합신소재구조학회 2020 복합신소재구조학회논문집 Vol.11 No.2

경주지진과 포항지진으로 수도관 파열과 상수도관 누수가 보고되었다. 따라서 상수도 시설의 지진안전성 확보는 지속적이고 안정적인 물공급을 위하여 중요한 이슈이다. 상수도관은 주로 도로 하부나 일반 성토지반에 매설되어있기 때문에 지진파에 의한 변형뿐만 아니라, 지반의 영구변형, 사면의 불안정성 및 지반 액상화 등에 의한 배관의 굽힘 변형이 발생하게 된다. 이러한 배관의 굽힘 변형이 과도하게 발생 되면 배관 이음부 변위허용량을 초과하여 손상 및 누수로 이어지게 된다. 따라 서, 상수도관 이음부의 허용 변형각이 산출되어야 지진으로 인한 지반의 변형에 대하여 상수도관의 지진안전성을 정확하게 평가할 수 있다. 상수도 시스템은 현장 상황과 설치 여건에 따라 다양한 종류의 상수도관을 이용하고 있다. 그중 주철 상수도관은 오랜 기간 사용되고 개선되어 일반적으로 널리 사용되고 있다. 본 연구에서는 한국주철관공업(주)에서 제작한 EZ-LOK 조인트가 적용된 주철 상수도관에 대하여 4점 굽힘시험을 수행하였으며, 매설된 주철 상수도관의 내진 및 내침하 설계기준인을 참조하여 지진안전성을 평가하였다. Several ruptures and leaks of water pipes were reported in the Kyongju and Pohang earthquakes. Therefore, securing the seismic safety of water pipe facilities is critical for continuous and stable water supply. Water pipes are usually buried under the road or a fill-up ground. Therefore, the deformation by seismic waves, permanent deformation of the ground, and soil liquefaction cause the bending deformation of the water pipes. Excessive bending deformation can cause damage and leaks to the pipe joints. Therefore, the allowable deformation angle of the water pipe joints should be calculated to accurately assess the seismic safety of the water pipes for the deformation of the ground caused by the earthquake. The water pipe systems used various types of water pipes depending on the site and installation conditions. Cast iron water pipes have been in use for long, and improved products are commonly used. This study evaluated cast iron water pipes with EZ-LOK joints manufactured by Korea Iron and Steel Co., Ltd. using a four-point bending test method, and evaluated the seismic safety of buried cast iron water pipes referring to evaluation results and seismic design criteria.

iPVC 매립 상수도관의 내진 성능 및 내침하 성능 평가를 위한 시험적 연구

전법규,장성진,김재봉,주부석 한국구조물진단유지관리공학회 2020 한국구조물진단유지관리공학회 논문집 Vol.24 No.1

우리나라의 연평균 지진발생 횟수는 꾸준히 증가하는 추세이다. 최근경주와 포항에서 규모 5를 초과하는 지진이 발생하여 상수도관의 피해가 다수 보고된 바 있다. 따라서 국내에서도 상수도관의 지진에 대한 대비가 필요 할 것으로 판단된다. 상수도관은 상수도 공급시스템에 있어 혈관과도 같은 중요한 시설로서 다양한 규격과 재질의 배관으로 구성된다. 그러므로 지진에 의한 상수도관의 손상은 식수공급, 화 재진압 등의 문제를 일으키게 되며, 인명 및 재산피해를 유발하게 된다. 하지만 국내에서는 시험 검증 및 경험에 의해 매립상수도관의 내진 성능이 평가된 예를 찾아보기 어렵다. 지진에 의한 상수도관의 손상은 액상화와 단층과 같은 지반의 변위지배적인 거동으로 인하여 발생한다. 지진에 의한 상수도관의 주된 파손은 배관 이음부에 집중되며 특히 직경 200mm 이하 배관이 위험한 것으로 조사되었다. 따라서 본 연구에서는 호칭 150mm의 클램프로 고정된 이음을 가지는 iPVC 매립 상수도관에 대하여 시험적인 접근으로 내진 성능 및 내침하 성능을 평가 하였다. Water pipes are important facilities and consist of pipes of various specifications and materials. The annual average number of earthquakes in Korea is steadily increasing. Therefore, in case of the water pipe, it is estimated necessary to prepare for earthquakes. Damages to the water pipe by the earthquake can cause problems such as water supply and fire suppression, and cause damage to life and property. In Korea, however, it is difficult to find examples of seismic performance evaluation of water pipes based on experimental study. Damage to the water pipes by the earthquake is caused by the displacement-controlled behavior of the ground which is the liquifaction and fault lines. Especially, The damage to the water pipes by the earthquake is concentrated on the joint of the pipe. In particular, piping less than 200mm in diameter was found to be dangerous. Thus, in this study, the seismic and settlement performance of iPVC buried water pipes with fixed joints with a clamp of 150mm was evaluated with a test approach.

금속 벨로우즈 신축관이음의 저온조건 내진성능에 대한 실험적 연구

전법규,김성완,윤다운,주부석,유진석 한국복합신소재구조학회 2022 복합신소재구조학회논문집 Vol.13 No.6

Piping is a representative nonstructural element. Damage to pipes due to earthquake can be caused by inertia force, cyclic loads due to the phase difference between two support points, and relative displacement that exceeds the allowable deformation limit. In particular, many experimental studies have estimated that the failure mode of piping due to earthquakes is a low-cycle fatigue caused by large cyclic loads. Therefore, to prevent piping damage due to excessive seismic displacement, the application of a seismic separation joint or seismic separation assembly at a location where large relative seismic displacement can occur is required. Bellows, which are among the expansion pipe joints, can be applied as a seismic separation joint. In this work, an experimental study was conducted to analyze the change in seismic performance due to the temperature difference of a three-ply metal-bellows expansion joint. A gradual amplification cyclic-loading test was performed under room-temperature condition, and the same test was performed under a low-temperature condition of −20°C. The test results were compared, which confirmed that the displacement performance of the three-ply metal-bellows-type expansion joints could be reduced by approximately 10% under a low-temperature condition of −20°C. 대표적인 비구조요소인 배관의 지진에 의한 손상은 관성력과 두 지지점 사이의 위상차에 의해 작용하는 반복하중 그리고 허용변형량을 초과하는 상대변위 등에 의해 발생할 수 있다. 특히 주요 손상모드는 큰 반복하중에 의한 저주기피로임이많은 실험적 연구를 통하여 알려졌다. 따라서 과도한 지진변위에 의한 배관의 손상을 방지하기 위하여 지진상대변위가 발생할수 있는 위치에 지진분리이음 또는 지진분리장치의 적용이 요구된다. 신축관이음 중 하나인 벨로우즈는 지진분리이음으로 적용할 수 있다. 본 논문에서는 3ply 금속 벨로우즈 신축관이음의 온도차에 의한 내진성능의 변화를 분석하기 위한 실험적 연구를수행하였다. 상온환경에서 점진증폭 반복하중재하실험을 수행하였으며, -20°C의 저온조건에서 동일한 실험을 수행하고 그 결과를 비교하였다. 실험 결과로부터, -20°C의 저온환경에서 금속벨로우즈의 변위성능은 약 10% 저하될 수 있음을 확인하였다.

[기초강좌] 기계 및 전기설비의 내진성능 시험방법

전법규 한국소음진동공학회 2018 소음 진동 Vol.28 No.3

Estimation of the Vibration Serviceability Deflection Limit of a High-speed Railway Bridge Considering the Bridge-Train Interaction and Travel Speed

전법규,김남식,김성일 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.2

The static and dynamic displacements of high-speed railway bridges, which are determined by the load conditions, travel speed, and span, may cause passenger discomfort when they are excessive. In the Korea Railway Bridge Design Specifications, the allowable deflection is based on the train travel speed. It is, however, not sufficient for considering the vibration serviceability. The Eurocodes has also been quoted in the design guidelines of the Korean Honam High-speed Railway (KRNA, 2007). For the determination of the vibration serviceability of a passenger train, the Eurocodes proposes a deflection limit based on the vibration serviceability obtained from the ratio of the deflection to the span and considers the bridge–train interaction. However, the maximum speed and maximum span in the Eurocodes are 350 km/h and 120 m, respectively. Moreover, it does not provide a detailed process for determining the deflection limit based on vibration serviceability. It is therefore difficult to use the deflection limit as the design limit in increasing the span and travel speed. Hence, to ensure passenger comfort and enable changes in railway techniques, it is necessary to develop a vibration serviceability-based deflection limit that flexibly responds to changes in the railway environment regarding bridge span and travel speed. This study was conducted to determine the deflection limits of Korean railway bridges based on their vibration serviceability and considering the bridge–train interaction and increase in travel speed. In this paper, the bridge– train transfer function is developed using a simplified bridge–train model comprising a single mass–spring system. It is then verified by dynamic analysis of the bridge–train interaction. A parametric study and bridge–train dynamic interaction analysis are used to determine the correlation between the vertical acceleration of a car body and the bridge displacement with increasing travel speed. In addition, the vertical acceleration of the car body is shown to increase with increasing travel speed, and an amplification coefficient of the vertical acceleration of the car body is suggested. Further, a vibration serviceability deflection limit for high-speed railway bridges is developed in this paper using the transfer function and the amplification coefficient. Here, the deflection and vibration of the bridge are assumed to be respectively sinusoidal and harmonic. The suggested vibration serviceability deflection limit is also compared with those in the Eurocodes and the Shinkansen.

원추형 마찰진자베어링의 내진성능평가

전법규,장성진,박경록,김남식,정득영 한국지진공학회 2011 한국지진공학회논문집 Vol.15 No.2

본 연구에서는 중요 통신장비의 지진발생시 파손 및 성능저하를 방지하기 위하여 구조물로 전달되는 가속도를 조절할 수 있는 CFPBS(Cone-type Friction Pendulum Bearing System:원추형 마찰진자베어링)를 개발하고 내진성능을 검증하였다. CFPBS는 기존의 FPS(Friction Pendulum System)와 다르게 원추형으로 제작되었으며 보다 큰 마찰력을 얻기 위하여 마찰면에 패턴을 음각하였다. CFPBS의 고유성능을 파악하기 위하여 4개의 CFPBS가 하나의 개체를 이루도록 제작된 지진격리장치를 이용하여 자유진동시험을 수행하였다. 운동방정식으로부터 유도된 CFPBS의 이론식과 Newmark-{\beta} Method를 이용하여 내진성능을 검증하기위한 MATLAB7.0 기반의 동적 수치해석프로그램을 제작하였으며 CFPBS의 제작 시 원하는 성능을 발휘할 수 있도록 간략화된 CFPBS의 설계식을 제안하였다. 수치해석을 통한 CFPBS의 내진성능평가를 위하여 건축구조설계기준(KBC-2005)의 최대지진규모에 해당하는 인공지진파를 생성하고 검증하였다. El Centro NS(1940)와 Kobe NS(1995), 인공지진파 등을 사용하여 CFPBS의 상부질량과 경사각을 매개변수로 하는 수치해석을 수행하였다. 수치해석의 결과를 토대로 CFPBS의 내진성능을 평가하였으며 수치해석의 결과와 설계식을 이용하여 동일한 조건에서 얻어진 결과를 비교분석하였다. In this study, a CFPBS (Cone-type Friction Pendulum Bearing System) was developed which controls the acceleration delivered to the structure to prevent damage and degradation of the critical communication equipment in case of an earthquake. The isolation performance of the CFPBS was evaluated by numerical analysis. The CFPBS was manufactured in the shape of a cone differenced from the existing FPS (Friction Pendulum System), and a pattern was engraved on the friction surface. The natural frequencies of the CFPBS were evaluated from a free-vibration test with the seismic isolator system consisting of four CFPBSs. In order to verify its earthquake-resistant performance, a numerical analysis program was created from the equation of the CFPBS induced from the equations of motion. A simplified theoretical equation of the CFPBS was proposed to manufacture the equipment which could demonstrate the necessary performance. Artificial seismic waves satisfying the maximum earthquake scale of the Korean Building Code-Structural (KBC-2005) were created and verified to review the earthquake-resistant performance of the CFPBS by numerical analysis. The superstructural mass of the CFPBS and skew angle of the friction surface were considered for numerical analysis with El Centro NS (1940), Kobe NS (1995) and artificial seismic waves. The CFPBS isolation performance evaluation was based on the results of numerical analysis and the executed comparative analysis between the results from numerical analysis and the simplified theoretical equation under the same conditions.