Influence of tuning of passive TLD on the seismic vibration control of elevated water tanks under various tank-full conditions

Abstract

This paper focuses on the seismic vibration control of elevated water tanks (EWTs) by the passive tuned liquid damper (TLD). Because of the fluctuating water content, the EWT is a variable-mass system resulting in a continual modification of its natural frequencies. The problem of identifying the optimal tuning of the damper for robust performance over the range of fill depths of interest in the EWT is addressed here. The nonlinear model based on shallow water wave theory simulating sloshing motion of the liquid (here water) in the TLD is utilized. The sloshing of water in the EWT itself is considered by modeling the EWT as a two-degree-of-freedom system, one representing the lateral vibrational mode of the supporting tank structure, tank container and impulsive mass of the water and the other denoting the fundamental sloshing mode of the water. A time domain study on a realistic reinforced concrete shaft supported EWT with TLD subjected to harmonic and recorded accelerogram input indicates that the TLD achieves significant response reduction and that it should be tuned to the structural frequency corresponding to the half-full to three-fourth full tank condition for robust performance. Copyright © 2016 John Wiley & Sons, Ltd.