The floating roofs are used in large aboveground oil storage tanks to prevent evaporation of the content.The single−deck floating roofs,which are considered herein,consists of a thin circular plate called a deck attached to a buoyant ring of box−shaped cross section called a pontoon.Under the accumulated rain water condition,the deck is deflected largely,and both its edge part and the pontoon are compressed circumfer-entially.Since the load condition due to the rain water depends on the

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... d deck shape,it is difficult to find the unique equilibrium condition.This paper describes the deformation analysis for the single−deck floating roofs under the accumulated rain water condition using the axisymmetric shell finite element method.The load incremental method,in which the equivalent nodal forces due to the rain water converges to identify to the rain water load derived from the deflected deck shape,is used.