Local buckling in cylindrical shells may occur elastically or plastically, mainly depending on the diameter to wall thickness ratio. In offshore structures plastic local buckling is mostly the governing criterion. In thin walled shells such as silos and tanks, local buckling may occur at stresses below the yield stress (elastic buckling). In this paper, the focus is on local buckling limits in both elastic and plastic local buckling. A survey of available test results and differences in various design standards is given. Reasons for the scatter found in experiments are identified. There is a need for more harmonization in design standards, focusing on the practical needs for each application.
Tubes in structural applications not only need sufficient strength, but also sufficient deformation capacity to allow for redistribution of stresses and loads. Such redistribution is important because in structural applications such as trusses and frames, the stresses are not only the result of the design loads, but often are also caused by loads that are usually not taken into account in the design. Examples are temperature differences, uneven settlements of supports and stresses due to welding. Also the type of analysis has an influence on the requirements for the deformation capacity. Plastic design methods are based on the possibility of local plastic deformations to obtain an optimal distribution of forces in the structure (normal forces, bending moments and shear forces). To obtain optimal stiffness and strength in bending and in axial compression (column buckling), the diameter to wall thickness ratio (D/t) is chosen as high as possible. The limiting factor is local buckling and the limitations in load carrying capacity and deformation capacity that comes with local buckling. The higher the D/t ratio is chosen, the lower the strain at which local buckling will occur. In other words, the lower the deformation capacity is.
