STRUCTURAL CONTROL AND HEALTH MONITORING Struct. Control Health Monit. 2006; 13:682–692 Published online 7 December 2005 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/stc.105 Semi-active neurocontrol of a base-isolated benchmark structure Heon-Jae Lee 1, * ,y , Guangqiang Yang 2 , Hyung-Jo Jung 3 , Billie F. Spencer, Jr. 2 and In-Won Lee 1 1 Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea 2 Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Matthews Ave., Urbana, IL 61801, U.S.A. 3 Department of Civil and Environmental Engineering, Sejong University, Seoul 143-747, Korea SUMMARY In this paper, a new semi-active control strategy for seismic response reduction using a neurocontroller and MR dampers is proposed. The proposed control system adopts a training algorithm based on a cost function and sensitivity evaluation algorithm to calculate the desired control force. A clipped algorithm is then employed to induce the MR damper to generate approximately the desired control force by selecting appropriate command voltage. The proposed semi-active neurocontroller was applied to a benchmark building installed with linear elastomeric isolation system. Comparing with passive and sample controller, numerical simulation results have shown that the proposed scheme can significantly reduce the floor acceleration, base shear and building corner drift with a slight increase of base displacement. Copyright # 2005 John Wiley & Sons, Ltd. KEY WORDS: semi-active control; neuro-control; base-isolation; benchmark problem; MR dampers; semi- active damping devices INTRODUCTION One of the most widely implemented and accepted seismic protection systems is base isolation. Seismic base isolation [1,2] is a technique that mitigates the effects of an earthquake by essentially isolating the structure and its contents from potentially dangerous ground motion, especially in the frequency range where the building is most affected. In base isolation systems, nonlinear devices such as lead–rubber bearings, friction pendulum bearings, or high-damping rubber bearings are often used. The benefit of these types of bearings Received 31 December 2004 Revised 31 March 2005 Accepted 28 May 2005 Copyright # 2005 John Wiley & Sons, Ltd. *Correspondence to: Heon-Jae Lee, Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea. y E-mail: wildhawk@kaist.ac.kr Contract grant sponsor: National Science Foundation; contract grant number: CMS 99-00234 Contract grant sponsor: Korea Science and Engineering Foundation