Testing and modelling a semi-actively controlled steel frame structure equipped with MR dampers

Abstract

In this paper, analysis of the shaking table tests performed on a four storey, large-scale, steel mock-up, equipped with a bracing system including magnetorheological (MR) dampers operating both in passive and semi-active (SA) ON–OFF mode, is presented. The adopted SA control algorithm is derived from an ‘energy-based’ instantaneous optimal control process. After having described the testing set-up and the control algorithm, a critical overview of the experimental results is reported. In particular, by using SA-controlled MR dampers, large response reductions, with respect to the corresponding passive (ON state) control configuration, may be obtained both in terms of relative displacements (drifts) and absolute accelerations. Moreover, it is experimentally confirmed that use of SA control, not only reduces the maximum values of the considered response quantities, but extends the improvements to the complete time-histories. This satisfactory performance is obtained, even if some particular (and undesired) types of behaviour, shown and explained in the paper, have been detected during the test campaign. In order to completely understand the dynamical behaviour of the controlled structure and to predict its response, a detailed analytical model of the controlled mock-up is proposed and validated. Copyright © 2004 John Wiley & Sons, Ltd.