PSI - Issue 82

Addisu Bonger et al. / Procedia Structural Integrity 82 (2026) 30–36 Addisu et al. / Structural Integrity Procedia 00 (2026) 000–000

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based and poses risks particularly for tightly reinforced structures due to overcharging and uncontrolled energy release. These risks limit its use in urban areas (Uenishi et al., 2023). To address this, an effective and controllable technique for precise demolition of concrete, which is known as Electric Discharge Impulse Crushing System (EDICS), has been developed and is being used in practice (Sasaki et al., 2011). The EDICS system consists of a power generator, control panel, electric discharge generator and a wire connected cartridge. Inside the cartridge, there is a thin metal wire and a liquid explosive material nitromethane ( 3 2 ). The electric discharge generator can provide a pulse of 3,000 V. After an electric impulse is discharged into the cartridge within the hundreds of microseconds, the thin metal wire is vaporized, and the deflagration of nitromethane’s phase change is initiated (Tanaka et al., 2020). Then, high pressure is generated by rapid volumetric expansion and applied to demolishing targets. Since the pressure generated during the deflagration is lower than that of detonation, the destructive effect on a structure is rather mild. That makes the whole process more controllable compared to high explosives. This study focuses on the numerical simulation of concrete fracture in steel-concrete composites under blast loading caused by the deflagration of nitromethane. The simulation employs 3D dynamic nonlinear finite element analysis. The experimental findings obtained on two specimens presented in previous research (Wada et al., 2021) were utilized as a reference of verification and validation of the simulation. The study investigates the crack network development, the influence of pressurized gas, stress level in the stud dowels and in the steel girder and verifies its findings experimentally. 2. Scheme of numerical analysis and modeling The 3D nonlinear finite element analysis was performed to simulate the blast-induced fracture in concrete. This study employs a multiscale poro-mechanical modeling approach to investigate the response of concrete structures under blast loading. 2.1. Multiscale poro-mechanical modeling The analysis method in this study is based on a novel poro-mechanical approach to analyze blast induced fracture in concrete considering gaseous kinetics (Zazirej et al., 2024). In this method, the original framework by Biot (1941) and Biot (1963) extended to compressible fluid media with nonconstant density that varies according to pore pressure. The analysis method targets three specific aspects: (1) concrete as a nonlinear porous material with initial porosity; (2) multidirectional crack interaction across three dimensions; and (3) accounting for phase changes between liquid and gas. The poro-mechanical approach to analyze blast induced fracture in concrete considering gaseous kinetics is an extension of a multiscale integrated system (Maekawa et al., 2008) to consider the three issues as stated above. These complexities motivate the application of a multi-phase poro-mechanical approach, known for its success in nonimpactive scenarios. a b

Stemming Cartridge

Cartridge Stemming

Steel rebars

Steel rebars

Stud dowel

Stud dowel

D L = 100 mm

D L = 200 mm

Cartridge

Cartridge

Steel girder

Steel girder

Fig. 1. Dimensions of two referenced specimen [unit: mm] (a) specimen A; (b) specimen B (Wada et al., 2021)).