Impact of Horizontal and Vertical Rings on the Seismic Performance of Steel Tanks under Water Sloshing Effects

The combined responses of horizontal and vertical reinforcing rings to sloshing behavior in cylindrical steel tanks subjected to seismic excitations have been evaluated in this study. In this study, for the first time, the ratio of maximum stress to fluid height in different scenarios is investigated, and the effect of water level and the stress created in the tank wall are presented, which can be a basis for improving structural design. So, the phenomenon of sloshing water on cylindrical tanks was investigated in four different situations: tanks in their original state, with horizontal rings, with vertical rings, and with both. Seismic amplification of sloshing is a very important failure mechanism in these tanks. In this case, the system undergoes resonance at the tank’s fundamental frequency, and the seismic excitation can significantly amplify the sloshing effect, cause larger-than-expected fluid movement and increase the likelihood of tank failure. Sometimes, the rapid fluid discharge creates a relative vacuum above the fluid level, which affects the upper parts of the tank shell. This study investigates the influence of horizontal and vertical rings on steel tank performance, focusing on sloshing behavior. The results of this study indicate that horizontal and vertical rings significantly influence the seismic performance of steel tanks, considering the effect of water sloshing, and a water level at half the tank’s height is optimal for withstanding seismic events. Also, it was found that if the height of the fluid is 58% of the tank height in all four cases, the highest stress will be created in the tank wall under the effect of turbulence. Examining the stress created at different heights showed that if the water level in the tank is more than one-sixth of the height of the tank, the average ratio of the highest stress level to the height of the water in the tank will be about 0.93.