Study On Ultimate Strength And Residual Strength Of Hull Girder With Nonlinear Finite Element Methods

Some accidents such as collision and stranding may happen when the ship is sailing.These accidents will result in the damage of hull,in severe cases,personal security,economic loss and environmental pollution even be caused.With surging of numbers of large-tonnage ships and strengthening of awareness of environmental protection,the requests for residual strength of broken hull structures are continuously improved.The residual strength that is used as index for security of ships has gradually been paid attention.To study ultimate strength and residual strength of hull girder is a theoretical significance as well as a practical value for safety of life and goods at sea,reduction of environmental pollutionIn the CSR-H(Harmonized Common Structural Rules for Bulk Carriers and Oil Tankers)to be implemented immediately by CCS(China Classification Society),Smith’s method can be used to calculate ultimate strength and residual strength of hull girder,it can be replaced by nonlinear finite element method.In this article,nonlinear finite element method is used to calculate ultimate strength and residual strength of hull girder,study lateral load as well as double bottom effect.Its main ideas are as follows:(1)Nonlinear finite element method was used to study the ultimate strength and the results were analyzed by compareing nonlinear finite element method with the results by Smith’s method.These would lay a foundation for future study.(2)The lateral load’s effect on the ultimate strength of ship hull was studied and the results were analyzed by comparing ultimate strength of single-span model,single-class model and three-class model under 4 kinds of lateral loads.These indicate the nature of double bottom effect.(3)With single-span-collision model and single-span-stranding model,the effects of the lateral extent of damage,location and bracing on the residual strength were studied.With single-span model,three-span model,five-span model and single-class model,the effects of longitudinal extent of damage on the residual strength were studied.(4)The criterion of ultimate strength and residual ultimate strength of Smith’s method was studied.The safety factors of FEM about ultimate strength and residual ultimate strength of single-span model and one-class model were also discussed.