Evaluation of the seismic design forces of elevated water tanks based on the spectrum design of standard No. 2800-14 and publication No. 38-16 in the areas with an exceedingly high relative risk of earthquake

Abstract

Elevated tanks of liquid storage designed for higher seismic forces than buildings due to their ductility and low energy absorption capacity. So that for a tank with low ductility, 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 No. 2800-14, the fourth edition for elevated tanks of liquid storage behavior coefficient 2 and 3 considered. In the third edition of the publication No. 38-16 coefficients of behavior for elevated tanks presented in accordance with the standard No. 2800. The results showed that in standard No. 2800, the ratio of the base shear coefficient of the tank to the base shear coefficient of the ductile building in the 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 obtained in publication No. 38, 4 and 6, respectively. Also, 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 standard No. 2800.