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Adaptive base-isolation of civil structures using variable amplification

Kenneth K. Walsh and Makola M. Abdullah

Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, 32310, USA

Abstract: Semi-active dampers are used in base-isolation to reduce the seismic response of civil engineering structures. In the present study, a new semi-active damping system using variable amplification will be investigated for adaptive base-isolation. It uses a novel variable amplification device (VAD) connected in series with a passive damper. The VAD is capable of producing multiple amplification factors, each corresponding to a different amplification state. Forces from the damper are amplified to the structure according to the current amplification state, which is selected via a semi-active control algorithm specifically tailored to the system’s unique damping characteristics. To demonstrate the effectiveness of the VAD-damper system for adaptive base-isolation, numerical simulations are conducted for three and seven-story base-isolated buildings subject to both far and near-field ground motions. The results indicate that the system can achieve significant reductions in response compared to the base-isolated buildings with no damper. The proposed system is also found to perform well compared to a typical semi-active damper.

Keywords: adaptive systems; amplification; base-isolation; damping; earthquake resistant structures; multistory buildings; seismic isolation; structural control