Experimental study on dynamic behavior of buried concrete rectangular liquid storage tanks using shaking table

Abstract

Buried concrete rectangular liquid storage tanks are categorized as key elements in lifeline network for fluid storage, especially potable water. A large number of them were built in Iran before 1980, without taking any seismic considerations, which their performance after an earthquake is a matter of concern. Thus, understanding the seismic behavior of these tanks in terms of water tightness, serviceability conditions, damage levels, and downtime days in case of an earthquake is crucial from the perspective of post-earthquake performance. Furthermore, research into the behavior of such rectangular-shaped tanks is complicated mainly because of the soil–tank–water interaction and the presence of expansion joints. Hence in this study, a series of small-scale experimental tests, using 1 g shaking table, were provided to investigate the effect of amplitude and frequency of input excitation on model responses with regard to the water level, the buried depth, and the density of surrounding soil. The results presented the pattern of soil cracks and showed that empty tanks had greater displacements than full ones. In addition, better performance was observed in the tanks embedded deeper and in denser soil. The damping ratios in full-water tanks were obtained more than in empty ones. Finally, within the framework of this study, the experimental results were compared with ACI 350-6 code; the results of hydrodynamic pressure showed acceptable agreement between two methods, except at the resonance frequency. However, some discrepancy was observed in results related to the phase of the dynamic soil force.