Stress Analyses in Single Deck and Double Deck Floating Roofs Subjected to Earthquake Ground Motions


1 Department of Mechanical Eng., Faculty of Eng., Urmia University, Urmia, Iran

2 Department of Civil Eng., Faculty of Eng., Urmia University, Urmia, Iran


This paper investigates the stress pattern in circular single and double deck floating roofs excited by earthquake ground motion. Variational formulation is employed to derive the governing equations.  Response of the floating roofs is evaluated for different classes of ground motions including near field and far field records. Results indicate that far-field earthquakes produce larger wave elevation and different stress patterns emerge in the roof. It is found that the bending stresses in double deck roofs emerge in a smooth and approximately symmetric pattern with a peak around the mid-span. This pattern differs drastically with stress pattern in single deck floating roofs where several unpredictable local stress peaks arise.  The results could have practical implications in the design process of floating- roof cylindrical tanks.