عنوان مقاله [English]
The application of control systems, active or passive, in reducing structural vibrations has been explored during the last few decades; some of them being practically employed. However, in large structural systems, the transfer of data from the sensors located at different places in the system to the processors, and sending back the control signals to the actuators in a very short time, is of great concern. That is the main reason behind the new concept of segregation of original large structural systems into smaller controllable units. In this paper, besides reviewing existing algorithms for centralized active control of tall buildings, the concept of decentralized active control of large structural systems is elaborated, and its application to the control of 3-D structural models is demonstrated. For this purpose, while proposing a method to divide 3-D structural models into several substructures, a velocity-displacement feedback control algorithm is used to reduce the response of the sub-structures. In the considered performance index for derivation of the control algorithm, the weighting matrices are determined using the Lyaponuv function to guarantee the stability of the dynamic system. It is followed by a case study, in which the performance of the decentralized control is compared with that of the regular centralized control approach. It is assumed that the actuators are located on all floors. Extensive parametric studies are performed to determine the sensitivity of the proposed control algorithm to a number of parameters, such as the number and size of substructures, eccentricity, and type of earthquake records. The obtained results indicate that, in all cases, the control algorithm guarantees the stability of the structural models, and the performance of the centralized and decentralized control approaches are almost the same. The effect of eccentricity is investigated using a number of earthquake records. It is shown that more control forces are needed in eccentric buildings, caused by the lateral-torsional seismic response of the structural system. The optimization of the size and number of sub-structures, to minimize the required control forces, is not the aim of this study, and will be dealt with in future work. In the developed control algorithms, both the structural model and the control system are assumed to behave linearly, and no time delay is considered in activation of the actuators (active tendons). Matlab software was used for performing the numerical analysis.