Numerical investigation of the effect of shape and aspect ratio on the dynamic response of concrete liquid storage tanks under near field earthquakes

One of the important factors in these damages is the incorrect prediction of liquid fluctua-tions in tanks. In this research, the dynamic analysis of concrete water storage tanks under near-field earthquakes has been done. The finite Element model of the studied tank is de-veloped in ABAQUS software considering the interaction of structure and fluid. Concrete tanks with cylindrical, square, and rectangular sections with the same storage volume are considered. These models are considered with two filling levels of 40 and 90%. To investi-gate the performance of the considered concrete tanks under near-field earthquakes with different characteristics, two groups of near-field earthquakes are selected for time history analysis. In the first group, 3 records of no-pulse near-field earthquakes and in the second group, 3 records of near-field earthquakes with forward-directivity effects were selected. The results of the time history analysis show that cylindrical tanks have performed better than square and rectangular tanks from the point of view of vertical and horizontal vibra-tion of the liquid surface inside the tank. Also, the results indicate that near-field earthquakes with the characteristic of forward-directivity compared to the no-pulse near-field earthquakes, lead to more horizontal and vertical vibration of the liquid surface inside the tank and also bring more acceleration to the walls of the tanks. In the same storage volume and in all forms of tanks, the amount of vibration of the liquid inside the tank is higher at lower filling levels. By reducing the aspect ratio, the response of both types of cylindrical and square tanks has shown a decrease. For square tanks with 40% filling, by reducing the aspect ratio from 0.583 to 0.357, the amount of vertical displacement of the liquid surface has decreased by about 20%. Also, for cylindrical tanks with a filling level of 40%, the amount of vertical displacement of the liquid surface has decreased by 29% corresponding to aspect ratio reduction from 0.517 to 0.3125.