Seismic analysis of steel cylindrical tanks with variable height to diameter ratio under the effects of far and near-field earthquakes taking into account the interaction of water and structure

Liquid storage tanks are very important structures for storing various types of fluids in urban and industrial areas. Therefore, designing, manufacturing, and evaluating their performance for different conditions is very important. In this study, the behavior of steel tanks with changes in the ratio of height to diameter of the structure under the effects of far and near field earthquakes has been analyzed and studied. For this purpose and for better analysis of these structures, 4 models of steel tanks with different height to diameter ratios and in empty and 90% full states have been subjected to seismic analysis using modeled ANSYS finite element software. To better investigate the trend of seismic effects on steel tanks, selected far and near-field earthquakes have been scaled to the same amount of 0.5g. The results showed that in empty tank conditions, by increasing the ratio of height to diameter to more than 1, the maximum values of displacement in the far and near-field earthquake are close to each other. The results also show the extraordinary importance of adding water to the response of steel tanks due to far-field earthquakes for a height to diameter ratio of more than 1. In most cases, by increasing the ratio of height to diameter of the structure and adding the fluid to the analysis, the values of the first main stress and the maximum reaction of the horizontal abutment in the two modes of analysis under the effects of the far and near-field earthquakes get closer to each other. The results show that in order to analyze and investigate steel tanks affected by earthquakes, in addition to near field earthquakes, far-field earthquakes should be studied and analyzed.