EXPERIMENTAL AND ANALYTICAL STUDIES OF FIXED-BASE AND SEISMICALLY ISOLATED LIQUID STORAGE TANKS

Experimental and analytical studies were conducted on seismically isolated and fixed-base liquid storage tanks. Shaking table tests were performed on a vertical cylindrical open-top steel tank 6ft in height and diameter, protected by four Triple PendulumTM bearings. Extensive parameter studies were performed, including comparisons of fixed-base and isolated model response to simulated ground motions of varying magnitude, time scale, and combination of components. Tests were repeated with three different water levels and for an empty tank. The responses of principal interest were base shear, water sloshing dynamics, tank deformation, tank uplift, and acceleration amplification at the top tank rim. The results of the experimental program were used to perform the corresponding parameter studies and to validate tank mechanical analog models used in design of liquid storage tanks. Experiment results show significant reductions in base shear, tank deformation, tank uplift, and acceleration amplification for seismically isolated tests as compared to corresponding fixed-base tests. Water sloshing dynamics show an increase in amplitude and complexity for multi-component excitation.