Stresses in Floating Roofs

A stress analysis is accomplished for pontoon-type floating roofs loaded by given volumes of rainwater. The unique equilibrium position for the loading is found by appropriately matching equilibrium positions for the circular inner membrane and the outer ring-shaped pontoon. The numerical solution of the coupled, nonlinear differential equations for the membrane requires the stipulation of several parameters at the center. A systematic procedure is developed to determine these parameters and the resulting overall equilibrium position and thus internal forces and stresses. The results for typical design configurations of several different tank diameters are presented and analyzed. The effects of varying the volume of rainwater and the density of the supporting fluid are also investigated.