scholarly journals SEISMIC RESPONSE ANALYSIS OF A SEISMIC ISOLATION SYSTEM FOR EVALUATING MECHANICAL ENERGY BALANCE

2017 ◽  
Vol 82 (733) ◽  
pp. 405-415 ◽  
Author(s):  
Takafumi HIRAKI ◽  
Kenji KANAZAWA ◽  
Haruyuki KITAMURA
Keyword(s):  
Energy Balance ◽  
Seismic Response ◽  
Seismic Isolation ◽  
Mechanical Energy ◽  
Response Analysis ◽  
Seismic Response Analysis ◽  
Isolation System

Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities: Part 3 — Seismic Response of Crossover Piping for Seismic Isolation System

2014 ◽  
Author(s):  
Akihito Otani ◽  
Teruyoshi Otoyo ◽  
Hideo Hirai ◽  
Hirohide Iiizumi ◽  
Hiroshi Shimizu ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Evaluation Method ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Isolation System ◽  
Isolation Systems ◽  
Seismic Isolation Systems

This paper, which is part of the series entitled “Development of an Evaluation Method for Seismic Isolation Systems of Nuclear Power Facilities”, shows the linear seismic response of crossover piping installed in a seismically isolated plant. The crossover piping, supported by both isolated and non-isolated buildings, deforms with large relative displacement between the two buildings and the seismic response of the crossover piping is caused by two different seismic excitations from the buildings. A flexible and robust structure is needed for the high-pressure crossover piping. In this study, shaking tests on a 1/10 scale piping model and FEM analyses were performed to investigate the seismic response of the crossover piping which was excited and deformed by two different seismic motions under isolated and non-isolated conditions. Specifically, as linear response analysis of the crossover piping, modal time-history analysis and response spectrum analysis with multiple excitations were carried out and the applicability of the analyses was confirmed. Moreover, the seismic response of actual crossover piping was estimated and the feasibility was evaluated.

Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 1 — Proposal of Analytical Models Based on Loading Tests

2018 ◽  
Author(s):  
Tsuyoshi Fukasawa ◽  
Shigeki Okamura ◽  
Takahiro Somaki ◽  
Takayuki Miyagawa ◽  
Masato Uchita ◽  
...  
Keyword(s):  
Seismic Response ◽  
Analytical Model ◽  
Three Dimensional ◽  
Analytical Models ◽  
Response Analysis ◽  
Seismic Response Analysis ◽  
Natural Period ◽  
Isolation System ◽  
Loading Tests ◽  
Rubber Bearings

This paper describes that the analytical model for the three-dimensional isolation system [1], which consists of thick rubber bearings, disc springs and oil dampers, is created through loading tests. The new-type analytical models of each element are proposed to improve the prediction accuracy of the seismic response analysis. The concept of the three-dimensional isolation system has been proposed to ensure the structural integrity for large reactor vessels. The primary specifications of the three-dimensional isolation system are a horizontal natural period of 3.4 s and a vertical natural period of 0.33 s. The investigations of horizontal isolation performances have been conducted for the various types of isolation devices, beginning with rubber bearings, whereas the previous studies focused on the vertical isolation performances are only a few. Hence, isolation characteristics, such as restoring force and damping force, should be clarified by loading tests using vertical seismic isolation elements, and analytical model to assess the seismic response should be identified on the basis of the loading test results. This paper presents a new analytical model with providing of the differential equations to improve the prediction accuracy and demonstrates the seismic performance, including beyond-design-basis ground motion, for the three-dimensional isolation system by the seismic response analysis.

Seismic Fragility Evaluation of Interface Pipes in Seismically Isolated NPPs by Using Scale Model Test

2015 ◽  
Author(s):  
Daegi Hahm ◽  
Min-Kyu Kim ◽  
In-Kil Choi ◽  
Bub Gyu Jeon ◽  
Hyoung Suk Choi ◽  
...  
Keyword(s):  
Seismic Response ◽  
Nuclear Power ◽  
Seismic Isolation ◽  
Response Analysis ◽  
Seismic Events ◽  
Piping System ◽  
Seismic Response Analysis ◽  
Secondary Systems ◽  
Inelastic Seismic Response ◽  
Isolation Device

Seismic isolation system can be an effective alternative to protect the NPPs (Nuclear Power Plants) against to the strong seismic events. Therefore, some research activities to adopt the seismic isolation concept to the design of the next generation NPPs have been progressed for last few years in Korea. Nuclear structures, secondary systems and components must remain undamaged during and after the SSE (Safe Shutdown Earthquake) event. The seismic events will cause the high seismic response in the stiff structural systems and extremely high demands of deformation on the safety-related secondary systems like piping components. If seismic isolation devices are installed in nuclear power plant for seismic stability, safety against seismic load of power plant may be improved. But in some equipment, seismic risk may increase because displacement may become greater than before installation of seismic isolation device. Therefore, it is necessary to select the equipment in which seismic risk increases due to increase in displacement by the installation of seismic isolation device, and perform a research on seismic performance evaluation of equipment. In this study, one of the typical Korean NPPs assuming the application of seismic isolation devices, and one of the interface piping systems which introduced this NPP was used for seismic analysis. The numerical models include representations of seismic isolation devices. In order to validation of numerical piping system model and defining failure mode & limit states, quasi-static loading tests were conducted on the scale-modeled piping components before the analysis procedures. The fragility analysis was performed by using results of inelastic seismic response analysis. Inelastic seismic response analysis was carried out by using shell finite element model of piping system considering internal pressure. The implicit method was used for the direct integration time history analysis. Generally, PGA (Peak Ground Acceleration) was used for seismic intensity of fragility curve. However, in the case of the displacement sensitive system, lateral displacement could be an useful alternative measure for estimation of probability of failure. Thus in this paper, fragility curves were plotted based on maximum relative displacement.

Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 6 — Development of High Speed Oil Damper for Isolated Building

2020 ◽  
Author(s):  
Tsuyoshi Fukasawa ◽  
Takahiro Somaki ◽  
Takayuki Miyagawa ◽  
Masato Uchita ◽  
Tomohiko Yamamoto ◽  
...  
Keyword(s):  
Seismic Response ◽  
Analytical Model ◽  
Seismic Isolation ◽  
Technical Problem ◽  
Testing Machine ◽  
Response Analysis ◽  
Damping Capacity ◽  
Test Machine ◽  
Test Results ◽  
Seismic Response Analysis

Abstract The design of seismically isolated structures has been required not only for damping devices with large damping capacities but also for those with high allowable velocities. This is because the seismic response assessment has been conducted using various ground motions, with high acceleration levels, to increase the structural integrity of buildings and components. However, the research focused on increasing the allowable velocity remains to be largely limited because the research involves a testing machine problem as well as a technical problem to increase the allowable velocity. To solve these problems, the authors have developed a new oil damper for seismic isolation buildings with an allowable velocity that is two times higher than commercially available oil dampers, which is the largest damping capacity class in Japan, using the test machine with one of the largest dynamic loading performance in the world. This paper demonstrates the availability of the proposed oil damper through the following items: The first is to clarify the damping force characteristics on the basis of the test results up to the maximum input velocity of 2.7 m/s. The second is to present the analytical model for the oil damper to apply to the seismic response analysis including the method to identify its variables. The third is to demonstrate the isolation performance through the seismic response analysis using the analytical model identified the variables obtained from the test results. These results imply that the proposed oil damper will be able to contribute to expanding the feasible design range for the isolation technology as well as increasing the seismic safety margin of the components for SFR.

SEISMIC RESPONSE ANALYSIS OF THE BUILDING FOUNDATION BASED ON THE DEFORMATION PERFORMANCE TESTS OF PHC-PILE

1999 ◽  
Vol 5 (9) ◽  
pp. 71-76
Author(s):  
Takao MATSUMURA ◽  
Shinichiro ASANO ◽  
Jun YAMADA ◽  
Masao KOBA ◽  
Koji ITO ◽  
...  
Keyword(s):  
Seismic Response ◽  
Response Analysis ◽  
Performance Tests ◽  
Seismic Response Analysis ◽  
Building Foundation
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