Evaluation of Seismic Design Forces of Liquid Storage Elevated Tanks based on Standard Design 2800 and Publication No. 38 in the Area with very High Relative risk of Earthquake

Generally, elevated tanks of liquid storage are designed for higher seismic forces than buildings due to their ductility and low energy absorption capacity. So that for a tank with low ductitlity, its base shear coefficient is about 6 to 7 times larger than the base shear coefficient of a ductile building and for a tank with high ductility, this ratio is about 3 to 4 times higher than all standards. In standard 2800, the fourth edition for elevated tanks of liquid storage behavior coefficient 2 and 3 is considered. In standard 2800, the fourth edition for air tanks of liquid storage behavior coefficient 2 and 3 is considered. In the publication, No. 38 coefficients of behavior for elevated tanks are presented in accordance with the standard 2800. The results showed that in standard 2800, the ratio of the base shear coefficient of the tank to the base shear coefficient of the ductile building in the relatively high risk zone for tanks with behavior coefficients of 3 and 2 in short periods was 3.5 and 5,25, respectively, while this value was obtained in No. 38 publications 4 and 6, respectively. The results also showed that the ratio of base shear coefficient of tanks to buildings in short periods for both behavior coefficients and four soil types in publication No. 38 was 14% higher than the results of the fourth edition of standard 2800