Verification of Seismic Response Reduction By Real-Time Hybrid Simulation of a Mid-Story Isolation With a Magnetorheological Rotary Inertia Mass Damper

Abstract eng:
Base-isolation systems show high performance of reduced floor acceleration and deformation of superstructures during periods of strong earthquake ground motion. However, against near-fault pulse ground motions of intra-plate earthquakes or long-period ground motions of inter-plate earthquakes, results of recent studies show that excessive displacement occurs in the base-isolation layer. A mid-story isolated system presents the benefit that the isolation layer is constructed mid-story: structural systems often differ between lower stories and higher stories. As described herein, the seismic response reduction performance of mid-story isolated buildings attributable to a semi-active control system was investigated using real-time hybrid simulation by a shaking table. A six-lumped-mass model simplifies the multi-story building with an isolation layer mid-story. Real-time hybrid simulation using an actual damper (2 kN max. damping force) and a four-story structural model (2 ton total weight) of the superstructure was conducted to verify the seismic response reduction performance of the system. The two-story structural model response under the isolation layer of the system was calculated using a digital signal processor (DSP), accounting for both the ground motion and the actual damper force in real time. In this real-time hybrid simulation, the calculation accuracy and time lag are also discussed. A semi-active control method using a rotary inertia mass damper filled with magnetorheological fluid (MR fluid) was proposed. The damper shows both a mass amplification effect attributable to rotational inertia and a variable damping effect attributable to the MR fluid. The damping force is controlled by the strength of the magnetic field applied to the MR fluid. The magnetic field strength is determined by the electric current, which is calculated using the proposed semi-active control method based on the respective velocities of the ground motion and of the isolation layer relative to the layer immediately underneath it. Real-time hybrid simulation results suggest that the response displacement of the structure above the isolation layer is reduced considerably without increasing the response acceleration of the entire structure against near-fault pulse and long-period ground motions. The proposed semi-active control using an MR rotary inertia mass damper was confirmed to be effective for mid-story isolated buildings. The control method achieves the objectives.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket