Minmax optimum design of active control system for earthquake excited structures

A minmax optimization method for the vibration control system considering uncertain dynamics is presented in this paper. In the proposed method, structural modeling errors and various excitations, which may cause performance degradation, are treated as plant parameters. The minmax problem considered in this study is not only to find an optimal controller that minimize structural responses but also to search the worst-case plant parameters that maximize structural responses, whereas the conventional optimal design usually deals with a minimization problem for a certain performance index. In order to solve the proposed minmax problem, the bimatrix co-evolution algorithm is adopted. It approximates the minmax problem as the bimatrix game between two fitness measures and finds the optimal solution effectively through the co-evolutionary process, as a result, the optimal controller and the worst-case plant parameters are searched simultaneously. Example design of an earthquake-excited building structure with active tendon control system is performed and comparative results of numerical simulation are presented to validate the proposed method. (C) 2012 Elsevier Ltd. All rights reserved.