Abstract:This research based on ABAQUS quasi-static analysis method for cargo hold area structure of FPSO main hull, a three-step strong frame model was established to study its ultimate bearing capacity under vertical bending moment and 30° bow wave, considering material nonlinearity and actual sea conditions in the vessel's working area.The relationship between vertical load and horizontal load in the combined load was determined by using the RAO ratio of bending moment directly calculated by the whole ship wave.The results show that the ability of arch bending moment is stronger when the structure is subjected to vertical load.When horizontal load is introduced, the resistance ability of the structure to vertical external load is reduced, and the influence on the extremely high bending moment of the mid-vertical is greater. When the ultimate bending moment occurs, the corresponding structure generally suffers buckling failure in a large area.The horizontal ultimate moment always appears before the vertical ultimate moment and the bilge structure effectively transits the joint load between the middle arch and the horizontal moment.