Buckling of fixed-roof aboveground oil storage tanks under heat induced by an external fire

This paper presents computational modeling and results of steel storage tanks under heat induced by an adjacent fire. In this research, modeling is restricted to the structural behavior of the tank, with emphasis on thermal buckling of the shell. Two tanks that buckled under a huge fire in Bayamón, Puerto Rico in 2009, are investigated in detail: a small tank with a self-supported conical roof, and a large tank in which the conical roof is supported by a set of rafters and columns. For a tank that is empty, the results show that a relatively low temperature is enough to produce static buckling of the shell. In pre-buckling states, the cylindrical shell has thermal expansion; at the critical state the displacements reverse and inwards displacements are observed at advanced post-buckling states. Parametric studies are performed to understand the influence of the shell thickness, the level of fluid stored in the tank, the area affected by fire in the circumferential direction, and the temperature gradient through the thickness. The buckling modes are compared with real deflection of tanks that were affected by fire.

► We model the effects of fire on thin-walled storage tanks with a fixed roof.
► We examine thermal buckling levels and buckling modes.
► Increasing the zone affected by heat or the level of fluid stored increases the critical temperature.
► A thermal gradient through the thickness decreases the critical temperature.
► Thermal buckling modes and critical temperatures are influenced by the adopted roof model.