Real-Time Hybrid Simulation of a Smart Base-Isolated Building

Abstract

Traditional passive base-isolation systems provide an effective means to mitigate the responses of seismically excited structures. A challenge for these systems can be found in accommodating the large base displacements during severe earthquakes. Recently, active base-isolation systems, combining actively controlled actuators with passive isolation bearings, have been shown experimentally to produce reduced base displacements, while maintaining similar responses of the superstructure obtained by the passive base-isolation systems. The active control devices used in hybrid isolation systems are typically driven by an external power source, which may not be available during severe seismic events. Another class of isolation systems is smart base isolation, in which semiactive control devices are used in place of their active counterparts. This control strategy has been proven effective against a wide range of seismic excitation; however, there has been limited effort to experimentally validate smart base-isolation systems. In this study, the focus is on experimentally investigating and verifying a smart base-isolation system using real-time hybrid simulation (RTHS), which provides a cost-effective means to conduct such experiments because only the portion of the structure that is poorly understood needs to be represented experimentally, while the reminder of the structure can be modeled using a computer. In this paper, a prototype magnetorheological damper is physically tested, while the isolated building concurrently is simulated numerically. A model-based compensation strategy is used to carry out high-precision RTHS. The performance of the semiactive control strategies is evaluated using RTHS, and the efficacy of the smart base-isolation system is demonstrated. This smart base-isolation system is found to reduce base displacements and floor accelerations in a manner comparable with the active isolation system without the need for large external power sources.