The Research About The Reliability Of Residual Ultimate Strength For The Damaged CSR Ships

With the vigorous development of the shipping industry,the risk of encountering collision and grounding accidents increases for CSR ships in the process of operating.In order to implement the rescue effectively and prevent hull structure from being further damaged,even the occurrence of loss events.As well as avoid property,life safety and marine ecological environment being caused greater damage.It is necessary to promote the safety evaluation to the residual ultimate strength for the damaged ship.For purpose of a reasonable level of the residual ultimate strength in the CSR-H specification be confirmed,a 308,000DWT VLCC tanker is taken as a study case in this paper.The structural reliability analysis method has been developed to assess the damaged hull.Main contents are as follows:(1)In this work the probability analysis of the damage extent specified by CSR-H is conducted according to the MARPOL Convention.(2)The probability characteristics of still water bending moment are counted,which is resulted from the single damaged cabin of the target ship(3)The forecast values of short-term and long-term wave bending moment are calculated that are based on the global sea spectrum with the WALCS software.As well as the extreme values prediction of a week and 25 years wave bending moment are derived with the extreme value theory.The approximate formula of a week wave bending moment is given at the same time.(4)The ultimate strength calculation program has been developed based on the Smith method.The probability characteristics of ultimate bending moment for each.damaged cabin of the target ship are counted using the Rosenblueth method(5)The reliability index of residual ultimate strength for each damaged cabin is calculated according to the improved FOSM and response surface methods.(6)The target reliability index of the residual ultimate strength of CSR-H specification is identified based on the actual ships testing result statistics and the reliability calculation results of the target ship.The partial safety factor of the residual ultimate strength is checked by the second level of law.