Copyright © IFAC Automatic Systems for Building the Infrastructure in Developing Countries, Istanbul, Republic of Thrkey, 2003 ELSEVIER IFAC PUBLICATIONS www.clscvicr.comflocalclifac SLIDING MODE CONTROL APPLIED TO MOTION CONTROL OF LINEAR STRUCTURAL SYSTEMS UNDER EARTHQUAKE EXCITATION Mahdi JaIili-Kharaajool, Siamak Feizi-Kbankande and Arasb Gbolami 1 1 Control & Intelligent processing Center of Excellence, Department ofElectrical and Computer Engineering, University of Tehran, P.D. Box 14395/515, Tehran, Iran Tel: (+98-21) 8020403, Fax: (+98-21) 8778690Turkey 2 Civil Engineering Dep., University ofTehran, P.D. Box 14395/525, Tehran, Iran E-mail address:mahdijalili@ece.uf.ac.ir Abstract: For dynamical systems expressed in state-space form or for systems with non-classical damping, the reduction of the structural model into the modal co-ordinates involves complex modal analysis with complex modal co-ordinates. In this paper, application of sliding mode control for vibration control of a linear structural system under earthquake excitation is investigated. The proposed controller is applied to a three-storey building structure and the motion of the floors under El-Centro earthquake is investigated. Simulation results show that using the proposed sliding mode controller the displacement of the floors is decreased significantly. This controller can be similarly applied for higher order building. Copyright © 2003IFAC Keywords: Sliding mode control, linear structural systems, motion control, earthquake excitation. I. INTRODUCTION The active structural control has emerged as a potential technology for enhancing structural functionality and structural safety of civil engineering structures against natural loadings such as earthquake loadings and wind loadings (Spencer, Dyke and Deoskar, 1997). Over the past few decades, various control algorithms and control devices have been developed, modified and investigated by various groups of researchers working in different parts of the world. Some of the control algorithms applied to building structural system have been presented in the literature, see (Aldemirl, Bakioglul and Akhiev, 2001; Guenfaf, Djebiri, Boucherit and Boudjema, 200 I; Lynch and Law, 2002). Sliding mode control (Edwards and Spurgeon, 1998) is a particular type of variable structure control systems that is designed to drive and then constrain the system to lie within a neighborhood of the switching function (Young, Utkin and QZgiiner, 251 1999). There are two main advantages of this approach. Firstly, the dynamic behavior of the system may be tailored by the particular choice of switching functions. Secondly, the closed-loop response becomes totally insensitive to a particular class of uncertainty (Bhatti, 1998; Drakunov and Utkin, 1992; Utkin, 1992; Jalili-Kharaajoo, Yazdanpanah and Ebrahimirad, 2003a,b). In addition, the ability to specify performance directly makes sliding mode control attractive from the design perspective. This design approach consists of two components. The first, involves the design of a switching function so that the sliding motion satisfies design specifications. The second is conserved with the selection of a control law, which will make the switching function attractive to the system state. The several analytical theories used for active control of civil engineering structures include optimal control, stochastic control, adaptive control, hybrid control and intelligent control (Journal of Engineering Mechanics, 1997; Housner, Soong and Masri, 1994). This work presents a sliding mode