A methodology for the reassessment of hull-girder ultimate strength of a VLCC tanker based on corrosion model updating

ABSTRACT

The paper presents a new methodology for reassessing hull-girder ultimate strength, assuming that new data become available on a specific time instance during the service life of the vessel. The calculation of ultimate strength is based on Smith’s incremental-iterative method and is examined in probabilistic terms. Uncertainties are associated with material yield strength, Young’s modulus and time-variant corrosion thickness wastage of structural members. The reassessment of ultimate strength is achieved by updating the time-variant corrosion model, taking into advantage on-site observations from thickness measurements reports, via the framework of Bayesian Updating. The results are discussed, along with recommendations for the validation of the suggested approach in practice. The proposed methodology is a tool to reassess the strength of vessel and can also be used for structural reliability analysis on vessels with similar operational and structural profile.

KEYWORDS:

• Corrosion model
• Bayesian updating
• ultimate strength
• reassessment