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Journal Articles

Accuracy of measuring rebar strain in concrete using a diffractometer for residual stress analysis

Yasue, Ayumu*; Kawakami, Mayu*; Kobayashi, Kensuke*; Kim, J.*; Miyazu, Yuji*; Nishio, Yuhei*; Mukai, Tomohisa*; Morooka, Satoshi; Kanematsu, Manabu*

Quantum Beam Science (Internet), 7(2), p.15_1 - 15_14, 2023/05

JAEA Reports

Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2022-057, 98 Pages, 2023/02

JAEA-Review-2022-057.pdf:8.5MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal" conducted in FY2021. The present study aims to construct a database for quantitative prediction of contaminated reinforced concrete inside the reactor building. In FY2021, data on deformation and water movement caused by drying and reabsorption of mortar were obtained to evaluate the mesoscale cracking behavior of concrete. A rigidbody spring model was used to develop a program that can consider changes in concrete age and temperature, water, and stress conditions. To evaluate the long-term penetration behavior of radionuclides into the factual matrix, data on sorption …

Journal Articles

Basic study on seismic respnse of soil-structure interaction system using equivalent linear three-dimensional FEM analysis of reactor building

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.

Journal Articles

Applicability of equivalent linear analysis to reinforced concrete shear walls; 3D FEM simulation of experiment results of seismic wall ultimate behavior

Ichihara, Yoshitaka*; Nakamura, Naohiro*; Moritani, Hiroshi*; Horiguchi, Tomohiro*; Choi, B.

Nihon Genshiryoku Gakkai Wabun Rombunshi, 21(1), p.1 - 14, 2022/03

AA2020-0911.pdf:8.99MB

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 $$gamma$$=2.0$$times$$10$$^{-3}$$. The equivalent linear analysis used herein underestimates the maximum displacement response at the time of ultimate fracture of approximately $$gamma$$=4.0$$times$$10$$^{-3}$$. 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.

JAEA Reports

Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal (Contract research); FY2020 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; The University of Tokyo*

JAEA-Review 2021-047, 127 Pages, 2022/01

JAEA-Review-2021-047.pdf:5.57MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Quantitative evaluation of long-term state changes of contaminated reinforced concrete considering the actual environments for rational disposal" conducted in FY2020. The present study aims to construct a database for quantitative prediction of contaminated reinforced concrete inside the reactor building. In FY2020, in chapter 3.1, in order to obtain the data for the evaluation of mesoscale cracking behavior, the equipment for the making and the measurement of the test specimens were prepared, the evaluation method was confirmed, and preliminary experiments were carried out.

Journal Articles

Deformation analysis of reinforced concrete using neutron imaging technique

Koyama, Taku*; Ueno, Kazuki*; Sekine, Mariko*; Matsumoto, Yoshihiro*; Kai, Tetsuya; Shinohara, Takenao; Iikura, Hiroshi; Suzuki, Hiroshi; Kanematsu, Manabu*

Materials Research Proceedings, Vol.4, p.155 - 160, 2018/05

 Times Cited Count:0 Percentile:0.00(Materials Science, Characterization & Testing)

Journal Articles

Application of neutron stress measurement to reinforced concrete structure

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*; Tasai, Akira*; Hatanaka, Yuichi*; Tsuchiya, Naoko*; Bae, S.*; Shiroishi, Sho*; Sakurai, Sonoko*; Kawasaki, Takuro; et al.

JPS Conference Proceedings (Internet), 8, p.031006_1 - 031006_6, 2015/09

The bond resistance between reinforcing bar (rebar) and concrete is one important parameter for examining integrity of the reinforced concrete structure, and is commonly evaluated by measuring the strain distribution along the rebar embedded in concrete. Here we present two types of applications of the time-of-flight neutron diffraction technique to measure the stress distribution of the rebar. It was demonstrated that bond deterioration around cracks developed in concrete can be evaluated by measuring the stress distribution along the embedded rebar using neutron diffraction. Furthermore, a change in the stress distribution along the rebar due to bond deterioration by corrosion was observed. The neutron diffraction technique is expected to become a novel method for measuring the stress (strain) of the rebar embedded in concrete, and will eventually provide insight into the actual phenomena on the reinforced concrete structures.

Oral presentation

Basic study on seismic response of soil-structure interaction system using equivalent linear three-dimensional fem analysis of reactor building

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.

Oral presentation

Bond stress evaluation of reinforced concrete using neutron diffraction

Suzuki, Hiroshi; Kanematsu, Manabu*; Mukai, Tomohisa*

no journal, , 

Oral presentation

Neutron engineering application for structural engineering of reinforced concrete structure

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*

no journal, , 

In the modern society, architectural and civil engineering structures such as reinforced concrete buildings require high seismic performance to minimize the risk exposed from urban earthquake hazards. In the reinforced concrete structures, the bond resistance between rebar and concrete is one important parameter for discussing the bond condition, and typically evaluated by measuring the strain distribution along the embedded rebar. In this study, the time-of-flight neutron diffraction technique was applied to the strain measurement of the rebar embedded in concrete. The three-dimensional deformation behavior of the embedded rebar including the axial and transverse strains was accurately measured under pullout loading. Furthermore, bond deterioration around the cracks in concrete and that around corroded rebar were successfully observed by measuring the strain distributions along rebar by neutron diffraction. The neutron diffraction technique is expected to be a novel strain measurement method for the rebar embedded in concrete for understanding actual phenomena on reinforced concrete structures.

Oral presentation

Recent progress on structural engineering studies of reinforced concrete using neutron diffraction

Suzuki, Hiroshi; Kusunoki, Koichi*; Kanematsu, Manabu*; Mukai, Tomohisa*

no journal, , 

11 (Records 1-11 displayed on this page)
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