Active control of irregular buildings considering soil-structure interaction effects

This paper analyzes the soil-structure interaction (SSI) effect on vibration control effectiveness of active tendon systems for an irregular building, modeled as a torsionally Coupled (TC) structure, subjected to base excitations such as those induced by earthquakes. An H-infinity direct Output feedback control algorithm through minimizing the entropy, a performance index measuring the trade-off between H-infinity optimality and H-2 optimality, is implemented to reduce the seismic responses of TC structures. The control forces are calculated directly from the Multiplication of the output measurements by a pre-calculated frequency-independent and time-invariant feedback gain matrix, which is obtained based on a fixed-base model. Numerical Simulation results show that the required numbers of sensors, controllers and their installation locations depend highly oil the degree of floor eccentricity. For a large two-way eccentric building, a one-way active tendon system placed in one of two frames farthest away from the center of resistance (C.R.) can reduce both translational and torsional responses. The SSI effect is governed by the slenderness ratio of superstructure and by the stiffness ratio of soil to superstructure. When the SSI effect is significant, the proposed control system can still reduce the structural responses, however, with less effectiveness than that of the assumed fixed-base model. Therefore, the TC and SSI effects should be considered in the design of active control devices, especially for high-rise buildings located on soft site. (C) 2009 Elsevier Ltd. All rights reserved.