Modal control of seismic building structures using active members

A control system which combines the concept of active members and a modal control scheme with direct output feedback is proposed. The method of computing the output feedback gain matrix to achieve the desired modal properties is presented. The problem of searching the achievable eigenvectors which are the best-fit of the desired eigenvectors is also investigated. A six-story building structure whose modal properties are condensed from a real steel building is taken as an example for numerical demonstration. As shown by the example, the seismic vibration of the building can be very effectively suppressed by merely using a single active member.