Measuring strain and stress distributions along rebar embedded in concrete using time-of-flight neutron diffraction

Significance statement

Neutron diffraction is known to be a nondestructive and noncontact method to measure strains and stresses in material, and this has been extensively utilized in various mechanical engineering works for understanding stress-state in material. We demonstrated in this paper that the neutron diffraction method is also applicable for measuring the strain distribution along rebar in the reinforced concrete without any effects on the bond condition, as an alternative technique to the typical strain gages. It has been demonstrated in our recent works that bond deterioration around cracks in concrete and around the corroded rebar can be evaluated by measuring the stress distribution along the embedded rebar using neutron diffraction (to be published in JPS Conference Proceedings). The neutron diffraction method will eventually provide insight into the actual phenomena regarding the reinforced concrete structures.

 

Measuring strain and stress distributions along rebar embedded in concrete using time-of-flight neutron diffraction-	- Advances in Engineering

 

 

 

 

 

 

 

 

 

 

 

 

 

Measurement Science and Technology Volume 25 Number 2, 2014.

H Suzuki1, K Kusunoki2, Y Hatanaka2, T Mukai3, A Tasai2, M Kanematsu4, K Kabayama5 and S Harjo6

Show Affiliations
1 Quantum Beam Science Directorate, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1195, Japan  and
2 Department of Architecture, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa 240-8501, Japan and
3 Department of Structural Engineering, Building Research Institute, 1 Tachihara, Tsukuba, Ibaraki 305-0802, Japan and
4 Faculty of Science and Technology, Department of Architecture, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan and
5 College of Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548, Japan and
6 J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1195, Japan

Abstract

In modern society, architectural and civil engineering structures such as reinforced concrete buildings require high seismic performance to minimize the ‘megarisk’ exposed from urban earthquake hazards. In the reinforced concrete structures, the bond resistance between rebar and concrete is one important parameter for discussing its performance and it has been typically evaluated by measuring the strain distribution along the embedded rebar. Here, we present in-situ strain and stress measurements for the rebar in reinforced concrete using time-of-flight neutron diffraction as a novel alternative technique to typical strain gauges. It was demonstrated in this study that the three-dimensional deformation behavior of the embedded rebar in normal-strength concrete, cured in air, can be accurately measured under pull-out loading using time-of-flight neutron diffraction. Wider applications of neutron diffraction in the structural engineering field are expected for advanced understanding of actual phenomena on reinforced concrete structures.

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