Behavior of Sloped-Bottom Tuned Liquid Dampers

Abstract

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 sloped-bottom 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.