Design Optimization of Tuned Liquid Column Ball Damper (TLCBD) For a Multi-Degree of Freedom Structure

Abstract

Construction of high rise structures is on rise in recent decades due to the modern needs and less availability of land areas. As the height of any structure increases, it gets more prone to earthquake and wind induced vibrations. Several modern techniques are used to control the structural vibrations, including active, passive and isolation damping systems. Tuned liquid column ball damper (TLCBD) is one of the passive control devices used for controlling the building vibrations induced from wind or earthquakes. TLCBD is a modified form of conventional tuned liquid column damper (TLCD) containing spherical ball in the mid of horizontal portion of U-shaped tube with liquid. The function of spherical ball is moving orifice that enhanced the vibration reduction effect by resisting the water motion in the TLCBD. This thesis presents the effect of TLCBD on the four-storey steel frame structure. TLCBD was tuned with the fundamental natural frequency and placed on the top storey of the primary structure. For performance optimization, three types of liquids and balls were used in the TLCBD including sugar solution, normal water, mustard oil, lead ball, steel ball and aluminum ball respectively. The effectiveness of the TLCBD was examined experimentally under different excitations including harmonic loadings and seismic excitations by series of shaking table tests. The acceleration response of TLCBD was calculated for each case against all loading conditions and compared with uncontrolled structure have no TLCBD for performance evaluation. Root mean square (RMS) and peak acceleration was calculated in all cases for each loading and each storey. Experimental results indicated that the TLCBD performance depends on both the liquid and ball used in it. Therefore both dense liquid and ball that are sugar solution and lead ball reduced the response better than other cases.