Annular Tuned Liquid Dampers for Elevated Tanks

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Elevated water storage tanks are extensively used in water supply facilities. These tanks are exposed to a wide range of seismic hazards and interaction with other sectors of built environment. Very few investigations have been carried out on the seismic resistance of elevated tanks. Earthquake damages to the tanks can cause unwanted events such as shortage of drinking and utilizing water and uncontrolled fires.Due to these reasons, this type of structure which is special in construction and in function from engineering point of view must be constructed to be resistant against earthquakes. In this project, the efficiency of an annular tuned liquid damper (ATLD) will be investigated in order to strengthen the elevated tanks against seismic loads. A tuned liquid damper (TLD) is a partially filled, water tank used as a vibration absorber in order to decrease the dynamic motion of a structure. The vibration of the structure under an external dynamic load causes sloshing motion of the liquid inside the TLD. By tuning the natural frequency of the sloshing motion to the natural frequency of the structure, the liquid motion imparts inertia forces approximately anti-phase to the external dynamic force, thereby reducing structural motion. The use of TLDs has increased due to their many advantages over other conventional damping devices. They are easy to install on existing structures, and need low maintenance and low operating costs. The proposed annular TLD can be easily installed in an elevated tank shaft without disturbing other mechanical devices or limiting the access to the reservoir. Although the construction of a TLD is simple, the liquid sloshing motion inside the TLD is characterized by a highly non-linear and complex nature. Due to the complex dynamic behavior of liquid-structure interaction and sloshing waves, the accurate prediction of their behavior is highly desired. The focus of this study is to investigate the behaviour of ATLDs for the application in elevated tanks using an advanced numerical program.