PSI - Issue 68

ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 68 (2025) 547–553

European Conference on Fracture 2024 Controlled horizontal and vertical cutoff of reinforced concrete structures by means of electric discharge impulses Koji Uenishi a,b, *, Hiroshi Yamachi c , Junichiro Nakamori c , Shintaro Sakaguchi b a Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8561 Chiba, Japan b Department of Aeronautics and Astronautics, The University of Tokyo, 7-3-1 Hongo, Bunkyo 113-8656 Tokyo, Japan c Sumitomo Mitsui Construction Co., Ltd., 518-1 Komagi, Nagareyama, 270-0132 Chiba, Japan Abstract For the efficient and controlled partial removal and renovation of old concrete structures, we have been developing several electric discharge impulses (EDI)-based techniques that guide three-dimensional wave interaction and ensuing dynamic fracture development precisely as desired. Here, by performing additional series of field experiments and corresponding finite difference numerical calculations, we show the mechanical “virtual interface” effect of reinforcing steel bars (rebars) on dynamic fracture development in reinforced concrete (RC) structures. If reinforced, the depth of overall fracture generated by EDI-induced waves may become relatively shallow and only the region sandwiched by an outer free surface and a virtual interface that is formed by the nearest rebars can be “sliced” or cut off, and the rebars, which are hard obstacles for later renovation work, can be exposed. In addition to the recently reported horizontal cutoff along a horizontal virtual interface formed by the topmost rebars, we show that if the relative positions of the EDI sources, free surfaces and rebars are rightly considered, the foremost rebars can function as a vertical virtual interface in a RC block, and the block can be vertically cut off along this vertical virtual interface and only the foremost rebars can be exposed efficiently. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers Keywords: Virtual interface; Dynamic disintegration; Controlled fracture; Wave interaction; RC structure European Conference on Fracture 2024 Controlled horizontal and vertical cutoff of reinforced concrete structures by means of electric discharge impulses Koji Uenishi a,b, *, Hiroshi Yamachi c , Junichiro Nakamori c , Shintaro Sakaguchi b a Department of Advanced Energy, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8561 Chiba, Japan b Department of Aeronautics and Astronautics, The University of Tokyo, 7-3-1 Hongo, Bunkyo 113-8656 Tokyo, Japan c Sumitomo Mitsui Construction Co., Ltd., 518-1 Komagi, Nagareyama, 270-0132 Chiba, Japan Abstract For the efficient and controlled partial removal and renovation of old concrete structures, we have been developing several electric discharge impulses (EDI)-based techniques that guide three-dimensional wave interaction and ensuing dynamic fracture development precisely as desired. Here, by performing additional series of field experiments and corresponding finite difference numerical calculations, we show the mechanical “virtual interface” effect of reinforcing steel bars (rebars) on dynamic fracture development in reinforced concrete (RC) structures. If reinforced, the depth of overall fracture generated by EDI-induced waves may become relatively shallow and only the region sandwiched by an outer free surface and a virtual interface that is formed by the nearest rebars can be “sliced” or cut off, and the rebars, which are hard obstacles for later renovation work, can be exposed. In addition to the recently reported horizontal cutoff along a horizontal virtual interface formed by the topmost rebars, we show that if the relative positions of the EDI sources, free surfaces and rebars are rightly considered, the foremost rebars can function as a vertical virtual interface in a RC block, and the block can be vertically cut off along this vertical virtual interface and only the foremost rebars can be exposed efficiently. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers Keywords: Virtual interface; Dynamic disintegration; Controlled fracture; Wave interaction; RC structure © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

* Corresponding author. Tel.: +81-4-7136-3824; fax: +81-4-7136-3824. E-mail address: uenishi@k.u-tokyo.ac.jp * Corresponding author. Tel.: +81-4-7136-3824; fax: +81-4-7136-3824. E-mail address: uenishi@k.u-tokyo.ac.jp

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of ECF24 organizers 10.1016/j.prostr.2025.06.095