Study On Reliability Enhancement Of Boxgirder Ships Under Cabin Inner Explosion

This thesis presents uncertainty analysis on the effects of box girderstructure in improving the reliability of naval vessels under cabin innerexplosion. The research is carried out from two aspects: structuralresponse and residual ultimate bearing capacity under inner explosion.The exceeding probabilities of both box girder structure ship andcommon structure ship are compared with each other, and the effects andmechanics of the reliability improvement are summarized.The uncertainty analysis in this work is based on the Monte CarloSimulation and the probabilistic analysis is done combining normaldistribution approach and maximum entropy approach. Individual casesinside the random sample are analyzed by numerical simulation, with thestructural response under inner explosion calculated via MSC.Dytran andresidual ultimate strength via non-linear finite element analysis, i.e.Abaqus CAE. The related theories and methodologies are presented indetail and some valuable conclusions are made.1. Box girder structure can significantly reduce the probability of large deformation on the strength deck under inner explosionlongitudinally and transversally; however, it does not seem tosignificantly reduce the possibility of fracture upon the explosionposition.2. Box girder structure can significantly increase the probability ofmaintaining a relatively high residual bearing capacity, i.e. ultimatebending moment and ultimate strain energy, after cabin inner explosion,thus improving the survivability of the ship.3. The effects of box girder structures in improving the residualultimate bearing capacity can be attributed to two aspects. On one hand,the box girder structures can restrict the strength deck deformation in alocal region and prevent large overall failure under inner explosion,leaving more valid bearing areas for subsequent loading. On the otherhand, the box girders provide extra stiffeness and strong restriction to thestrength deck, thus improving the overall bearing capacity.4. The results of the reliability analysis is in good coincidence withthe traditional deterministic analysis, which indicates that the uncertaintyanalysis framework in the present work is reasonable and can be appliedto anti-explosion assessment and design of naval vessels.