Abstract
In a previous paper, it was shown that circumferential in-plane stresses in the pontoon shell are caused by the circumferential bending deformation of the pontoon of a floating roof due to nonlinearity of sloshing. Furthermore, the validity of the present nonlinear sloshing analysis method was confirmed by comparing the theoretical results with results of a sinusoidal excitation test using a floating roof of a cylindrical storage tank with capacity of 15, 000kl.
In this paper, dependence of the nonlinear responses of the stresses on the slope of the pontoon is examined. Numerical results show that the decrease in the slope of the upper and lower plate of the pontoon results in decrease of the in-plane stresses of pontoon lower part. This stress reduction is due to the fact the circumferential out-of-plane bending moment is decreased by reducing the cone effect produced by the slopes of the upper and lower plates of the pontoon shell. A method for reducing stresses in the floating roof pontoon is proposed.
