The Method Research On Ultimate Strength Of Ship Structure Based On IACS Rules

Plates in ship structure due to the support of around frames will not be destroyed immediately after compressive buckling, but still bearing some compressive loads until collapse. The maximum load capacity just before collapse happenes is called ultimate strength. It can make full use of structure post-buckling performance, reflect the true strength margin, and satisfy the safety and economic requirement to the utmost extent, thus has been treated as a compulsory job by IACS. The article studied some methods for ship structure ultimate strength base on IACS common structure rules. The main job has been done is as follow:1) Discussed the design principle and technical requirement of ship structure during serviceability state, ultimate limit state, fatigue limit state and accidental limit state.2) Introduced ultimate strength calculation methods based on collapse modes, and analyzed continuous plate and continuous stiffened plate models with experiential formula method and energy theory method. Studied the influence of welding residual stress, lateral pressure, interaction between plate and stiffener members and plastic correction on structure ultimate strength.3) Compared the common structure rules of 08 revision and 06 version, worked out a visible program for ultimate strength in PCL language based on progressive collapse method in 08 revision rules. The model results of classical hull girder and buck carrier proved the program's reliability. Also, the influence of 08 revision rules on ultimate strength was analyzed.4) Studied the application of nonlinear FEM in ultimate strength field, computed the continuous plate, continuous stiffened plate, hull girder and buck carrier models with ABAQUS software, and compared the advantage and disadvantage among difference methods, namely theory formula method, progressive collapse method and nonlinear FEM method.5) Compared the existent effective width methods, and made a sensitivity analysis for yielding stress, two-dimensional stress ratio and stiffener type selection parameters.