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Yamakawa, Koki*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
no abstracts in English
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Moritani, Hiroshi*; Horiguchi, Tomohiro*; Choi, B.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 21(1), p.1 - 14, 2022/03
In this study, we aim to approximately evaluate the effect of nonlinearity of reinforced concrete structures through seismic response analysis using the equivalent linear analysis method. A simulation analysis was performed for the ultimate response test of the shear wall of the reactor building used in an international competition by OECD/NEA in 1996. The equivalent stiffness and damping of the shear wall were obtained from the trilinear skeleton curves proposed by the Japan Electric Association and the hysteresis curves proposed by Cheng et al. The dominant frequency, maximum acceleration response, maximum displacement response, inertia force-displacement relationship, and acceleration response spectra of the top slab could be simulated well up to a shear strain of approximately 
=2.0
10
. The equivalent linear analysis used herein underestimates the maximum displacement response at the time of ultimate fracture of approximately =4.010. Moreover, the maximum shear strain of the shear wall could not capture the locally occurring shear strain compared with that of the nonlinear analysis. Therefore, when employing this method to evaluate the maximum shear strain and test results, including those during the sudden increase in displacement immediately before the fracture, sufficient attention must be paid to its applicability.
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 6 Pages, 2021/08
Several large-scale earthquakes have occurred, such as the Niigataken Chuetsu-oki Earthquake in 2007 and the 2011 off-the-Pacific coast of Tohoku Earthquake. Therefore, a three-dimensional (3D) finite element model to evaluate the local response of the reactor building is currently being developed for seismic response analysis. In order to refine the 3D finite element model, it is important to verify the correspondence to the seismic observation behaviors. In this study, the authors analyze the basic response characteristics, such as the natural frequencies and modes of the reactor building, and evaluate the effects of the amplitude of the seismic excitation on the response characteristics based on seismic observation records. This is done to clarify the behavior of a reactor building during earthquakes. These analyses will assist in quantitatively evaluating the correlation between the natural frequency of the building and the amplitude of the seismic excitation. Furthermore, the ratios of rotational displacement and displacement caused by building deformation for natural modes are discussed.
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Moritani, Hiroshi*; Choi, B.; Nishida, Akemi
Frontiers in Built Environment (Internet), 7, p.676408_1 - 676408_14, 2021/06
The objective of this study is the improvement of response evaluations of structures, facilities and equipment in evaluation of three-dimensional seismic behavior of nuclear power plant facilities, by three-dimensional finite element method model, including separation and sliding between the soil and the basement walls. To achieve this, simulation analyses of Kashiwazaki Kariwa nuclear power plant unit 7 reactor building under the 2007 Niigataken-chuetsu-oki earthquake event were carried out. These simulation analyses consider soil-structure interaction using a three-dimensional finite element method model in which the soil and building are three-dimensionally modeled by the finite element method. It is found that basemat uplift is generated on east side of the basemat edge, and this has an important influence on the results. The importance is evidenced by the difference of local response in soil pressure characteristics beneath the edge of basemat, the soil pressure characteristics along the east side of basement wall and the maximum acceleration response at the west end of the embedded surface. Although, in this particular study, basemat uplift, separation and sliding have only a relatively small influence on the maximum acceleration response of embedded surface and the soil pressure characteristics along the basement walls and beneath the basemat, under strong earthquake motion, these influences can be significant, therefore appropriate evaluation of this effect should be considered.
moleculeOkada, Michio*; Moritani, Kosuke; Yoshigoe, Akitaka; Teraoka, Yuden; Nakanishi, Hiroshi*; Di
o, W. A.*; Kasai, Hideaki*; Kasai, Toshio*
Chemical Physics, 301(2-3), p.315 - 320, 2004/06
Times Cited Count：14 Percentile：41.22(Chemistry, Physical)O molecules adsorb dissociatively on Cu{1 0 0} surfaces to form the oxygen-saturated surface with the coverage of 0.5 ML. It has been found that the oxidation has proceeded more than 0.5 ML by using 2.3-eV-O molecular beams. The kinetics of the adsorption reaction was the first order. This reveals that the collision-induced adsorption results in the adsorption of only one oxygen atom. On the other hand, the reaction kinetics showed the second order in the case of 0.6-eV-O incidence. This implies that tentative molecular adsorption takes place in such low collision energy case.
Yamakawa, Koki*; Tsuchiya, Takashi*; Hiramatsu, Masako*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Yamakawa, Koki*; Tsuchiya, Takashi*; Hiramatsu, Masako*; Moritani, Hiroshi*; Saruta, Masaaki*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko; Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*
no journal, ,
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Yamazaki, Hiroaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Moritani, Hiroshi*; Yamakawa, Koki*; Saruta, Masaaki*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
Yamakawa, Koki*; Saruta, Masaaki*; Moritani, Hiroshi*; Iiba, Masanori*; Nishida, Akemi; Kawata, Manabu; Iigaki, Kazuhiko
no journal, ,
no abstracts in English
