Effect of top stiffening rings of open top tanks on critical harmonic settlement

Abstract

The purpose of this work is to investigate the effect of top stiffening rings of open top tanks on the critical harmonic settlement. First, the buckling behavior of a tank with a top stiffening ring is provided and the results are compared with that of the model with no stiffening ring. The results show that the critical harmonic settlement for the tank with a top stiffening ring is lower than that for the tank with no top stiffening ring. Moreover, the top stiffening ring plays a significant role on the critical harmonic settlement when the wave number is small, but plays a minor role on that when the wave number is large. Then, the imperfection sensitivity analysis is conducted to identify whether the top stiffening ring can decrease the sensitivity of imperfection. Meanwhile, the worst imperfection form for tanks subjected to harmonic settlement is reported. The results present that the weld depression has the most adverse effect on the settlement carrying capacity of tanks. Moreover, it is indicated that the top stiffening ring cannot always decrease the sensitivity of the imperfection. The sensitivity plots are related to harmonic wave numbers, as well as imperfection forms. Finally, the effect of top stiffening rings with different structure parameters on the critical harmonic settlement is reported, including the length and the thickness of the top stiffening ring. For the length of the top stiffening ring, the critical harmonic settlement versus the wave number decreases more and more slightly with the increasing length of the top stiffening ring. For the thickness of the top stiffening ring, the critical harmonic settlement versus the wave number decreases more and more mildly with the thickness of the top stiffening ring on the increase.