Numerical and experimental investigation on a novel seismic base-isolator made by the magnetic levitation technology

Abstract

The idea of reducing lateral stiffness to extend the natural period of structures is fundamental in using seismic base isolators in structural engineering. However, a perfect isolator with no horizontal stiffness is unrealistic due to the mechanical components in traditional isolators, such as rubber layers and springs. This research introduces the Maglev isolator, which uses magnetic levitation technology to explore a new way to achieve zero horizontal stiffness. To achieve this objective, finite element modeling was validated, leading to a system of two steel plates and ten coils, five on the upper plate and five on the lower, aligned to face each other. This configuration generated a repulsive force that suspended the system. The design’s stability was rigorously tested under static and dynamic loads in both time and frequency domains. After successful simulations in COMSOL, an active control mechanism was developed and evaluated in MATLAB to improve performance. Additionally, the seismic performance of a prototype was tested experimentally across two frequency ranges using a shaking table. The experimental results demonstrate that the isolated system achieves average reductions of 76% in absolute displacement and 73% in absolute acceleration compared to the input values. The Maglev isolator demonstrated remarkable efficacy at elevated frequencies, achieving a substantial decrease in both displacement (83% at 4 Hz versus 70% at 2 Hz) and acceleration (86% at 4 Hz compared to 60% at 2 Hz). This study confirms the novel base-isolator’s significant potential in reducing seismic energy transfer to buildings.