VIBRATION PRONE MULTI-PURPOSE BUILDINGS AND TOWERS EFFECTIVELY DAMPED BY TUNED LIQUID COLUMN-GAS DAMPERS
Ch. Fu and F. Ziegler
Center of Mechanics and Structural Dynamics, Vienna University of Technology, Austria-Europe
Abstract
Tuned mechanical dampers, TMD, are common practical passive devices to increase the effective structural damping. The sealed, tuned liquid column gas damper, TLCGD, became the cost-effective absorber of similar efficiency. Multi-purpose buildings and towers exhibit moderate or pronounced asymmetry even for a regular geometrical plan. Consequently, the floors are both, obliquely displaced and rotated about the vertical axis during earthquake or wind induced vibrations. The coupled, modal displacement and small rotation combine kinematically to a rotation about the floor’s modal center of velocity. If such a center falls outside of the floor (moderate asymmetry), the ideal position of the mid-plane of the U- or Vshaped TLCGD requires its normal distance from this center maximum. Pronounced asymmetry renders several modal centers within the floor plan: the novel (sealed, torsional) TTLCGD with its in plane curved piping section encloses the center for best efficiency
Keywords: Asymmetric building; space frame; wind and earthquake excitation; modal tuning, gas-spring effect; state space optimization