Investigating the effectiveness of LQG output-feedback active control for seismic alleviation of multi-structural buildings is the main purpose of this study. A general model of a shear-frame multi-structure as a lumped-mass planar system with movements in the path of the ground motion for the attached tree-building system is developed, first. Then an output- feedback controller based on the Kalman filter and optimal control theories is designed for the main structure, to guarantee the stability of the closed-loop system to achieve an arranged level of disturbance attenuation. Consequently, for investigating the effectiveness of the proposed method on the main and neighbor structures, some numerical simulations using historically recorded ground accelerations, are considered and the results will be discussed.
