This technology is an EMP shielding rebar grid selection method and system that builds a database of the Metal Grid Free Area Ratio (MGFAR) and the electromagnetic shielding effectiveness (SE) of concrete reinforced with various rebar grids of different diameters and spacings, then identifies the MGFAR value corresponding to a target SE to select the appropriate rebar grid for the concrete.
In South Korea, where the state of armistice persists, the risk of EMP attacks is constant, and lightning strikes can also damage electronic equipment. Conventional methods have included applying conductive paint to concrete surfaces or mixing in steel fibers to enhance shielding. However, it is difficult to verify the uniform distribution of steel fibers before and after construction, and mixing ratios exceeding 1.5% can lead to clumping and internal voids, reducing structural strength. Additionally, increasing concrete thickness has inherent design limitations.
This technology derives a sub-modeling curve representing SE versus MGFAR, then obtains a main modeling curve by applying regression equations corrected for errors based on frequencies (400, 600, 800, 1000 MHz) and the number of overlapping rebar grids (one or two). From this curve, the rebar spacing, diameter, and number of layers are quantitatively determined to meet the target SE. The selection process includes configurations where two grids are overlapped with offset intersections or arranged with varying spacing. Applicable to the design of critical infrastructure such as data centers, communication facilities, military and government bunkers, and power control rooms, this method achieves required EMP shielding rates through rebar specifications alone, without the need for conductive material treatments or increased wall thickness.
This invention was developed with support from the Ministry of Land, Infrastructure and Transport for the development of EMP-shielding concrete materials, components, structures, and systems.
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