原子力施設を対象とした鉄筋コンクリート免震基礎の耐震性能
Seismic isolation systems are effective in ensuring seismic safety of nuclear power plants. In cases where a nuclear reactor building is seismically isolated, it is necessary to identify seismic characteristics of not only the seismic isolator but also the reinforced concrete foundation that support...
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Veröffentlicht in: | Nihon Kenchiku Gakkai kōzōkei ronbunshū 2017, Vol.82(733), pp.433-440 |
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Sprache: | jpn |
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Zusammenfassung: | Seismic isolation systems are effective in ensuring seismic safety of nuclear power plants. In cases where a nuclear reactor building is seismically isolated, it is necessary to identify seismic characteristics of not only the seismic isolator but also the reinforced concrete foundation that supports the seismic isolator. Few experimental studies have been made, however, to evaluate the coupled characteristics of a seismic isolator and its reinforced concrete foundation, and no study has dealt with the large deformation range leading up to breaking of laminated rubber bearings at a nuclear power plant. This study focuses on the combination of a seismic isolator and its reinforced concrete foundation (pedestal) designed for use at a nuclear reactor building. A series of static loading tests was carried out by using specimens designed to simulate a realistic combination of a seismic isolator and a pedestal.The test specimens were 1/2-scale models of a design example shown in JEAG4614-2013, and four specimens were used. The seismic isolator used was a lead rubber bearing 800mm in diameter, and a pedestal measuring 1200mm by 1200mm was used. The test parameters were the level of compressive axial stress made to act on the seismic isolator, compressive strength of concrete, and the existence or non-existence of reinforcing bars at the top of the pedestal. Basically, compressive axial stress was assumed to be a constant stress of 10MPa to simulate the stress at the center of a building. In the specimen designed to simulate the region near the edge of the building, compressive axial stress was increased proportionately to simulate large deformation. The compressive strength of concrete of 42MPa was assumed to be a standard value, and an experiment using a 60MPa specimen was also conducted to evaluate the effect of high-strength concrete.The test results revealed the behavior of pedestal under strains up to the rubber breaking level (shear strain= 450%) exceeding the limit assumed at the design. The test results also clarified the cracking patterns, load-deformation relationship, the strain behavior of concrete and reinforcement at and near the pedestal surface in contact with the seismic isolator. And a design method for preventing bearing failure of concrete under high compressive axial stress was proposed. From the results of this study, the following conclusions can be drawn:(1) The reinforced concrete foundation showed structural integrity within the range as |
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ISSN: | 1340-4202 1881-8153 |
DOI: | 10.3130/aijs.82.433 |