There is an increasing demand for ice strengthened tankers. This is driven by the growing oil exports from Russia, environmental impacts due to increased traffic, recent harsher ice conditions in Baltic Seas, and the accelerated IMO single hull tanker phase-out schedule. As a result, it has become very important to design ice strengthening side structures that are more producible while maintaining adequate safety and integrity. Plastic deformation theory has been successfully used in design formulations for ice impact loads. Although ice strengthening design standards have accepted a certain level of permanent deformations to the side shell, the allowable permanent deformations are not explicitly identified. The latest advances in computer technology and computational software have made it possible to explicitly calculate the permanent deformations of structures, which forms the basis for more rational designs. Industry needs have prompted the American Bureau of Shipping to develop the Guidance Notes on Nonlinear Finite Element Analysis of Side Structures Subject to Ice Loads. These Guidance Notes provide detailed instructions for structural modeling, material nonlinearity, ice loads, boundary conditions, and acceptance criteria. Alternative design is regarded as acceptable if its deformation is comparable, i.e., equal to or smaller than, the base design that fully complies with the intended ice class requirements. Using the design of side longitudinals within the ice belt, the necessary steps of nonlinear FEM analysis for ice strengthening tankers are illustrated with details. In addition, these Guidance Notes are applied to the evaluation of some design variations and designs for different ice classes. Discussions are provided to address more balanced designs, repeated ice loads, and design of other structural components.
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