| The aging ship in normal sea sustains accidents (such as grounding, collision and being attacked), which lead to damage. The first consequence is reduction of structural capacity, and the hull may collapse globally to wreck. On the other hand, it may cause the leaking of the oil so as to pollute the environment. Avoiding the waste of the financial resources, and suffering heavy causalities, it is especially important and adequate for ship safety assessment using the ultimate strength.Over the past several decades, there has been growing interest in the ultimate strength for damaged hull? At present much significant developments have been made on the hull ultimate strength. And there has been given out some simple analytical formulations. But, those theoretical researches can only be used as the state of design, not rather apply to other cases of the damaged hull.This subject is concerned chiefly with the study of the ultimate strength analysis and reliability assessment for the damaged hull. For the bad ship hull, the distributions of gravity and buoyancy will change, and it may cause the load effects (still water shear force and bending moment) to change obviously. The emphasis of this paper is based on the theory of floatability, apply Vlasov's calculation method to determine the floating parameters of damaged hull, and calculate still water bending moment and shear force. This paper has developed a series of programs to analyze the ultimate strength and reliability for the damaged hull.On the basis of the analysis and discussion, ultimate longitudinal strength analysis and reliability assessment and prediction are made for the intact hull (new construction) and damaged structure (grounding) of an existing oil crude tanker. Expected results of examples are obtained. The results of this paper can supply the departments of the transport ship with the significant values, which make the captain to assess the risk for the ship hull and work out a plan for rescue. |
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