Behavior of Sloped-Bottom Tuned Liquid Dampers

The performance of a tuned liquid damper (TLD) with a sloped bottom of an angle of 30° with the horizontal is investigated experimentally. The sloped-bottom TLD was found to be just as effective in dissipating energy as the familiar box-shaped TLD. While the liquid motion of a box-shaped TLD resembles that of a hardening spring, the behavior of the sloped-bottom TLD resembles that of a softening spring. These different behaviors are due to different nonlinear effects: the amplitude dispersion effect and the wave runup effect onto the sloped surface, respectively. The sloshing force created by the motion of the slopedbottom TLD was found in limited shaking table experiments to be comparable with that created by the equivalent box-shaped TLD, even though the net fluid mass of the sloped-bottom TLD is less than one half that of the box-shaped TLD. This behavior appears to be caused by the greater effective liquid mass involved in the sloshing motion in the sloped-bottom TLD.