Shaking table tests on a full-scale steel frame with a multi-dimensional hybrid base isolation system employing intelligent magnetorheological control

Conventional isolation systems face challenges such as excessive displacements due to low horizontal stiffness during strong earthquakes and limited adaptability from fixed damping parameters. To overcome these limitations, this study proposes a novel multi-dimensional hybrid base isolation system employing intelligent magnetorheological (MR) dampers to enhance the seismic resilience of large-scale steel structures. The system combines multi-dimensional earthquake isolation and mitigation devices (MEIMD) with semi-active MR dampers. To optimize the synergistic coupling between MR dampers and seismic isolation bearings, this study develops an intelligent cooperative control strategy. It employs an H2/LQG control algorithm integrated with a segmented current-level optimal strategy to achieve adaptive damping force modulation. Full-scale shaking table tests on a four-story steel frame (70-ton, 13.05 m height) were conducted under various seismic intensities, to compare performance of the intelligent hybrid system against passive isolation. Results demonstrate that intelligent hybrid control system significantly reduces peak accelerations by up to 28.14 % at lower floors and 15.8 % at the roof compared to sole passive control. The MR damper exhibited robust energy dissipation capacity, and the hybrid system effectively suppresses base drift (20 % reduction under MCE-level Rg waves), effectively resolving the detrimental structural impacts associated with excessive lateral displacement in conventional base isolation systems. This achievement provides an intelligent damping solution for seismic design in high-rise buildings, combining displacement control with adaptive regulation capabilities.