Resonant Transmission Through a Single Subwavelength Slit for Varied Metallic Permittivities and Its Modal Orthogonality

This article investigates resonant transmission phenomena through a single metallic subwavelength slit when the permittivity of a real metal varies. The single metallic slit is utilized as a metal–insulator–metal waveguide, and a mode-matching technique is employed to obtain the transmitted power. The periodic resonant transmission phenomena (in terms of the metallic plate thickness) are solved, and the resonances can be understood by their guide wavelengths. Even when the permittivity of the real metal includes imaginary parts (i.e., metal with loss), the resonant transmittances are obtained. However, the peaks of the transmittances decrease, as the plate thickness increases. The orthogonal relationship of an incomplete orthogonal set is maintained despite metallic loss (given a relatively small amount of loss), due to the complex permittivity of the real metal.

Metallic Slit-Plate Dampers: Damage Evaluation with Metal Magnetic Memory Technique and Application to Structures with Rocking Columns

Inelastic deformation of metallic materials is one of the most effective mechanisms for the dissipation of energy input to a structure by an earthquake. Metallic dampers are special devices that resort to this source of energy dissipation, proving to be a cost-efficient solution for the seismic protection of structures. Two important issues arise when implementing metallic dampers in real structures: (1) Inelastic deformations cause damage that must be quantified after an earthquake to decide upon their eventual replacement; (2) dampers must possess an energy dissipation capacity large enough to endure severe earthquakes. This paper focuses on a particular type of metallic damper consisting of slit-plates made of stainless steel, applied to reinforced concrete frames with rocking columns at the first story. In particular, a new damage index based on the metallic magnetic memory (MMM) method is proposed and validated experimentally to quantify the damage of slit plate dampers subjected to cyclic loadings. Further, the seismic response of a frame with rocking columns that incorporate the damper is obtained to demonstrate that it can endure severe earthquakes without failing, and to emphasize the relevance of the proposed MMM damage index that would make its replacement after a severe earthquake unnecessary.