HYBRID CONTROL OF SEISMICALLY EXCITED STRUCTURES BY VIBRATION CONFINEMENT

A hybrid (active and passive) control strategy, aiming at confining and suppressing simultaneously the vibratory motion in flexible structures, is proposed. These structures are assumed to be composed of parts that are sensitive to vibrations that result from an initial energy distribution and/or external disturbances. The design objective is to devise a feedback scheme that leads to transferring the vibrational energy in the sensitive parts to the remaining ones (non-sensitive parts) of the structure. In order to keep away from the build-up of transferred energy into the non-sensitive parts, the feedback scheme considers, along with the confinement, the suppression of vibrations in the whole spatial domain of the structure. A case study for a three-story building is considered to examine the effect of the number of the added bracing elements and their spatial placement on the vibration confinement of the structure. It is demonstrated that the use of a single bracing element attached directly to the floor gives a relatively better reduction of vibrational amplitudes of the floors. A parametric study is carried out to observe the influence of the various parameters of the control strategy on the simultaneous confinement and suppression of structural vibrations. The robustness of the proposed control strategy is analyzed and then tested for the three-floor structure.