Design of amplified structural damping using optimal considerations

A method is suggested to reduce the structural seismic response using viscous dampers with their effect magnified with mechanical levers (lever arms). The lever arms are used to magnify the drift and the drift velocities transferred from the structure to the dampers thus producing larger energy dissipation in smaller devices. The increase of energy dissipation in each unit results in a reduction of the number of units necessary to achieve the same reduction in structural response, or it results in a reduction of the size of dampers required for the same purpose. The use of the proposed technique permits one to reduce the number of frame bays obstructed by diagonal or Chevron bracing elements. An optimal design procedure, based on the linear quadratic regulator (LQR) technique, is proposed in this study to obtain the initial properties of the viscous dampers. The study presents the amplification and the contribution of the construction details to such amplification. A seven-story structure model with the proposed system was simulated numerically in order to check the damping efficiency. The numerical example shows that using the lever arms for dampers' connection, it yields significant reduction in the structural response, very close to that designed according to the LQR strategy.