Shaking Table Experiments for Examination of Uplift Response of Cylindrical Liquid Storage Tanks Due to Uniaxial Horizontal Ground Motion

Shaking table experiments were conducted for investigating the uplift response of cylindrical liquid storage tanks. The uplift of tank bottom plate may cause severe damage to lower part of the tank shell and/or the tank bottom plate. In addition, crack of the bottom part of the oil storage tank may cause significant leakage of content liquid and large-scale fire that would be difficult to extinguish. Therefore, a method is needed to determine whether the tank bottom part will be cracked due to strong motion. Because the amount of maximum uplift displacement and the number of uplifts are required to evaluate the accumulative damage to the tank bottom part, several methods for calculating the tank rocking response due to ground motion have been proposed. However, these conventional methods may not be able to explain the actual uplift response. Furthermore, there are few reports that verify the calculation accuracy of the conventional methods. A 2000L steel tank model was used in the shaking table experiments. Its height, diameter and thickness are 1.68m, 1.25m and 4.5mm, respectively. The liquid height was changed so that the aspect ratio of content liquid was 0, 0.6, 0.9, 1.2. The tank model was shaken with several harmonic waves of different amplitudes. Time-histories of uplift displacement and rocking acceleration were obtained for more than 45 experimental cases. Regarding the uplift commencement condition, the results of the experiments compared with the results calculated by the conventional methods. The comparison results show that the uplift commencement condition of the conventional methods must be reconsidered. In addition, the calculation method called Yoshida - Taniguchi method which calculates time-history of uplift displacement is validated.