Alternative Tuned Absorbers for Steady State Vibration Control of Tall Structures

Abstract

Two forms of damped vibration absorbers are evaluated to describe their value in reducing steady state vibration of tall buildings. The first model contains a set of two identical one-degree-of-freedom elements symmetrically mounted in a horizontal plane on either side of the building’s long axis. An alternate model has independent translational and torsional elements mounted at the building’s center. Damping parameters are included for building fundamental bending and torsion modes to evaluate those effects on response. The sensitivity of absorber performance to absorber-building mass ratio μ is of interest to minimize the size of the absorber. Performance of the absorber models was compared based on maximum transmissibility and a quality integral, which is an integrated transmissibility over a frequency spectrum based on amplification at a point on the building top. Small damping in the structure aided absorber performance. Quality is quite insensitive to mass ratio and absorber damping for a building damping ratio in the order of 0.05. Damping is to be reduced in the absorber to improve quality for small absorber-to-building mass ratios when building damping becomes small.