Seismic Performance Evaluation of Piping System Crossing the Isolation Interface in Seismically Isolated NPP

함대기,; 박준희,; 최인길,

doi:10.5000/eesk.2014.18.3.141

Cited by 13 publications

(6 citation statements)

References 10 publications

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“…In addition, the log-standard deviations representing the randomness and the uncertainty exist individually for each defined safety factor. Such individual log-standard deviations can be integrated into a single log-standard deviation using the square root of the sum of the squares (SRSS) method, as shown in Equations (9) and (10). Due to such characteristics of this method, this is called the seismic fragility method by a variable separation.…”

Section: Epri Sov Methodsmentioning

confidence: 99%

“…Specifically, a study was conducted to investigate the limit states of T-joints [5,6], elbows [7,8], etc., which were structurally fragile components of the piping system, through a dynamic cyclic test for the piping. In addition, studies have been carried out to experimentally and analytically investigate the earthquake responses of actual piping subjected to ground shaking [9][10][11]. Based on these findings, several groups performed studies on the seismic fragility of piping systems that considered the uncertainties of earthquake loading and the piping model to assess the probabilistic seismic safety of piping [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Kwag

Ryu

2020

Applied Sciences

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In the event of an earthquake, it is essential to accurately assess the seismic fragility of piping systems to ensure the continued safety of society. When evaluating the seismic fragility of a piping system, which is generally a secondary structural system, this should mainly be an integrated model that includes both the primary structural frames and the secondary ones, unlike the primary structural system of a building. Hence, the piping seismic fragility evaluation has an issue in that it takes considerable computational time because numerical analyses must be performed on a relatively complex model. Given this background, the purpose of this study is to propose an efficient piping seismic fragility analysis method by utilizing the existing seismic fragility analysis method and the Bayesian updating concept. In order to verify the validity of the proposed method, it was applied to a building–piping coupled structural system example, and its results were analyzed and compared with the results of the existing method in terms of accuracy and efficiency. As a result, the proposed method showed a similar accuracy compared with the existing method while significantly reducing the numerical cost of nonlinear seismic response analyses necessary for these results.

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Section: Epri Sov Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Kwag

Ryu

2020

Applied Sciences

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“…In order to secure the seismic safety of the interface piping system, its seismic performance must be verified, because the occurrence of a large relative displacement is expected [27][28][29]. In general, the interface piping system consists of straight pipes and fittings (elbows and tees).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Limit State of a Six-Inch Carbon Steel Pipe Elbow in Base-Isolated Nuclear Power Plants

et al. 2021

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The installation of base isolation systems in nuclear power plants can improve their safety from seismic loads. However, nuclear power plants with base isolation systems experience greater displacement as they handle seismic loads. The increase in relative displacement is caused by the installed base isolation systems, which increase the seismic risk of the interface piping system. It was found that the failure mode of the interface piping system was low-cycle fatigue failure accompanied by ratcheting, and the fittings (elbows and tees) failed due to the concentration of nonlinear behavior. Therefore, in this study, the limit state was defined as leakage, and an in-plane cyclic loading test was conducted in order to quantitatively express the failure criteria for the SCH40 6-inch carbon steel pipe elbow due to low-cycle fatigue failure. The leakage line and low-cycle fatigue curves of the SCH40 6-inch carbon steel pipe elbow were presented based on the test results. In addition, the limit state was quantitatively expressed using the damage index, based on the combination of ductility and energy dissipation. The average values of the damage index for the 6-inch pipe elbow calculated using the force−displacement (P–D) and moment−relative deformation angle (M–R) relationships were found to be 10.91 and 11.27, respectively.

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“…In particular, there is a high risk of damage to the crossover(interface)-piping connecting the isolated part to the non-isolated part. Under this background, a study was carried out to evaluate the seismic safety of the crossover-piping of a seismic isolated nuclear power plant [15]. In addition, finite element analysis was performed to evaluate the seismic safety of the pipe system of the nuclear power plant [16,17].…”

Section: Introductionmentioning

confidence: 99%

Seismic Performance of Piping Systems of Isolated Nuclear Power Plants Determined by Numerical Considerations

et al. 2021

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The interest in the seismic performance of nuclear power plants has increased worldwide since the Fukushima Daiichi Nuclear Power Plant incident. In Korea, interest in the seismic safety of nuclear power plants has increased since the earthquake events in Gyeongju (2016) and Pohang (2017). In Korea, studies have been conducted to apply seismic isolation systems to ensure seismic safety while minimizing the design changes to nuclear power plants. Nuclear power plants with seismic isolation systems may have a higher seismic risk due to the failure of the piping system in the structure after a relatively large displacement. Therefore, it is essential to secure the seismic safety of pipes for the safe operation of nuclear power plants. The seismic safety of pipes is determined by seismic fragility analysis. Seismic fragility analysis requires many seismic response analyses because it is a statistical approach to various random variables. Typical numerical conditions affecting the seismic response analysis of pipes are the convergence conditions and mesh size in numerical analysis. This study examined the change in the seismic safety of piping according to the numerical conditions. The difference in the seismic response analysis results of the piping according to the mesh size was analyzed comparatively. In addition, the change in the seismic fragility curve of the piping according to the convergence conditions was investigated.

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Seismic Performance Evaluation of Piping System Crossing the Isolation Interface in Seismically Isolated NPP

Cited by 13 publications

References 10 publications

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Efficient Seismic Fragility Analysis for Large-Scale Piping System Utilizing Bayesian Approach

Evaluation of the Limit State of a Six-Inch Carbon Steel Pipe Elbow in Base-Isolated Nuclear Power Plants

Seismic Performance of Piping Systems of Isolated Nuclear Power Plants Determined by Numerical Considerations

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