Research On The Progressive Collapse Behavior Of Ship Hull Girder In Waves

With the maximization of ship size,the value of ship itself and carried cargos becomes higher and higher.Furthermore,the protection of the marine environment is much stricter.These demand higher requirements to the structural safety of ship.The ultimate load-carrying capacity of ship hull girder is of great significance to ensure the safety of ship structures in extreme seas,which has been a hot point in ship structural strength research field.Therefore,using appropriate methods to evaluate the ultimate load-carrying capacity of ship hull girder accurately is the premise and basis to enhance the structural safety of ship.The research will contribute to more accurately predicting the ultimate load-carrying capacity of the hull girder.Once the progressive collapse behavior of ship hull girder is determined,the structural materials can be allocated rationally,thus leading to design a ship with rational structure,light-weight and high-reliability.Model test and numerical simulations are combined in this paper to truly and comprehensively conduct the research on the progressive collapse behavior of hull girder in waves.To achieve the research goals,main attention and energies have been devoted into the following aspects:(1)At first,the ideas and processes of designing the steel test model used to perform the progressive collapse test of the hull girder in the wave were established.On this basis,the structural characteristic and collapse performance of the flat-type ship with large block coefficient and large openings were combined with the conditions of wave tank and the preliminary design of test model was presented.The feasibility of the preliminary design was evaluated by comparing the longitudinal moment acted on the ship with the ultimate strength of ship hull girder.(2)Based on the fact that the preliminary design failed to fulfill the objective of the test,many modified schemes were put forward through analyzing of influencing factors of the ultimate load-carrying capacity of hull girder and the external loads.The feasibility assessments of these modified schemes were performed and the final design plan was drawn by considering the actual factors including manufacturing cost,transportation and test conditions etc.The steel test model was constructed accordingto the final design plan.(3)The structural responses of ship under hydrostatic loading conditions and the progressive collapse behavior of hull girder in waves was analyzed through using the numerical calculation method,obtaining the corresponding structural response of hull girder under hydrostatic loading and in waves respectively.(4)Test schemes for the hydrostatic loading and the progressive collapse of ship hull girder were formed based on the numerical calculation results.Subsequently,the hydrostatic loading test and the progressive collapse test of ship hull girder in waves was conducted in the wave tank.The external loads and structural responses were measured in the process of performing the collapse test of ship hull girder in waves to get an insight into the diversification characteristic of the external loads and structural responses during the process of the progressive collapse of ship hull girder in waves.(5)The ship structural responses obtained from the test were compared with the numerical simulation results.The variation of stress of ship structure,ship hull girder's ultimate load-carrying capacity and the collapse mode were analyzed when ship hull girder collapsed in waves.Based on the analyzed results,the process of the progressive collapse of ship hull girder in waves was explored as well.