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Ichihara, Yoshitaka*; Nakamura, Naohiro*; Nabeshima, Kunihiko*; Choi, B.; Nishida, Akemi
Transactions of 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
The objective of this study is to evaluate the applicability of the equivalent linear analysis method for reinforced concrete, which uses frequency-independent complex damping with a small computational load, to the seismic design of reactor building of the nuclear power plant. To achieve this, the three-dimensional finite element analyses of the soil-structure interaction system focusing on the nonlinear and equivalent linear seismic behavior under an ideal soil condition were performed for Kashiwazaki-Kariwa nuclear power plant Unit 7 reactor building. From these results, the equivalent linear analysis method showed a generally good correspondence with the nonlinear analysis method, and the effectiveness of the method was confirmed.
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Nabeshima, Kunihiko*; Choi, B.; Nishida, Akemi
Kozo Kogaku Rombunshu, B, 68B, p.271 - 283, 2022/04
This paper aims to evaluate the applicability of the equivalent linear analysis method for reinforced concrete, which uses frequency-independent hysteretic damping, to the seismic design of reactor building of the nuclear power plant. To achieve this, we performed three-dimensional FEM analyses of the soil-structure interaction system, focusing on the nonlinear and equivalent linear seismic behavior of a reactor building under an ideal soil condition. From these results, the method of equivalent analysis showed generally good correspondence with the method of the nonlinear analysis, confirming the effectiveness. Moreover, the method tended to lower the structural stiffness compared to the nonlinear analysis model. Therefore, in the evaluation of the maximum shear strain, we consider that the results were more likely to be higher than the results of nonlinear analysis.
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.
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.
Ikawa, Nozomu*; Mukai, Yoichi*; Nishida, Akemi; Hamamoto, Takuji*; Kano, Toshiya*; Ota, Toshiro*; Nakamura, Naohiro*; Komuro, Masato*; Takeuchi, Masato*
Proceedings of 12th International Conference on Shock and Impact Loads on Structures (SI 2017) (USB Flash Drive), p.259 - 268, 2017/06
Accidental actions on building structures involve impact and explosion loads. The design loads due to impact are determined by experiment data, impact simulation and energetics approach. These loads are presented in the form of load-time (F-t) curves caused by collision and explosion. It is assumed that the structure is rigid and immovable and that impacting body absorbs all the energy (i.e., hard impact condition is supposed), because this assumption gives conservative results in general. Responses of individual structural members directly-subjected to an impulsive load are evaluated. These responses are classified into three types; impulsive response, dynamic response, and quasi-static response. The maximum responses are basically estimated by direct integration method with a single-degree-of-freedom (SDOF) model. The procedure of the SDOF modelling based on the classification of types of members and failure modes is proposed in AIJ guideline.
Nishida, Akemi; Ohashi, Yasuhiro*; Obi, Hirotoshi*; Takeuchi, Yoshitaka*; Kano, Toshiya*; Ryuzaki, Hibiki*; Ota, Toshiro*; Kishi, Tokumitsu*; Komuro, Masato*; Nakamura, Naohiro*
Kenchikubutsu No Taishogeki Sekkei No Kangaekata, p.161 - 202, 2015/01
Though design guidelines for earthquake and wind loads are specified for buildings, the guideline for impulsive load as explosion and impact is not specified yet in architectural field. This document corresponds to Chapter 8 of the book titled "Introduction to Shock-Resistant Design of Buildings" which made towards the impact design guideline. Some design examples are presented to illustrate the applicability of the tentative guideline for impulsive loads. Two buildings - a steel frame and a reinforced concrete frame building structures - located at the corner of a crossroads are selected. Dynamic responses and the corresponding damage states are illustrated for the cases of two buildings subjected to impact loads due to road vehicle crashes, internal and external explosions. The idea has been shown in this document are those that can be applied to nuclear facilities.
; Iijima, Tsutomu; Naohiro Hirakawa*; Nakamura, Tomoo*; Masao Nozawa*
Journal of Nuclear Science and Technology, 1(3), p.108 - 109, 1964/00
no abstracts in English
Ishikawa, Jun; Kurosawa, Naohiro*; Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo; Watanabe, Atsushi*
no journal, ,
no abstracts in English
Ishikawa, Jun; Kurosawa, Naohiro*; Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo; Watanabe, Atsushi*
no journal, ,
no abstracts in English
Torii, Tatsuo; Kido, Hiroko*; Yokoyama, Naomi*; Kurosawa, Naohiro*; Akita, Manabu*; Nakamura, Yoshitaka*; Morimoto, Takeshi*; Ushio, Tomoo*; Kawasaki, Zenichiro*
no journal, ,
To evaluate the influence to which radon and its decay products cause the thunderstorm activity, a large area diffusion model of radon is constructed for an Australian northern part that is one of the most frequent region of the thunderstorm in the world. The advection and diffusion analysis of radon in the atmosphere was carried out, and it compared it with the measured result of the radon concentration in the region from the dry season to the rainy season.
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Nabeshima, Kunihiko*; Choi, B.; Nishida, Akemi
no journal, ,
This study aims to evaluate the applicability of the equivalent linear analysis method for reinforced concrete, which uses frequency-independent hysteretic damping, to the seismic design of reactor building of the nuclear power plant. To achieve this, we performed three-dimensional FEM analyses of the soil-structure interaction system, focusing on the nonlinear and equivalent linear seismic behavior of a reactor building under an ideal soil condition. From these results, the method of equivalent analysis showed generally good correspondence with the method of the nonlinear analysis, confirming the effectiveness. Moreover, the method tended to lower the structural stiffness compared to the nonlinear analysis model. Therefore, in the evaluation of the maximum shear strain, we consider that the results were more likely to be higher than the results of nonlinear analysis. In this presentation, we describe the effectiveness and problems of the equivalent linear analysis method using three-dimensional FEM analysis of the soil-structure interaction system.
