Buckling of thin-walled silos and tanks under axial load : some new aspects

The strength of thin-walled cylindrical shell structures is highly dependent on the nature and magnitude of imperfections. Most importantly, circumferential imperfections have been reported to have an especially detrimental effect on the buckling resistance of these shells under axial load. Due to the manufacturing techniques commonly used during the erection of steel silos and tanks, specific types of imperfections are introduced into these structures, among them circumferential weld-induced imperfections between strakes of steel plates. A study on several factors influencing the buckling of silos and tanks was carried out using the finite-element method. The interaction between neighboring circumferential weld imperfections was investigated, and it was found that the influence on the buckling behavior depended on the strake height in relation to the linear meridional bending half-wavelength and the depth of the imperfection. The shape of localized circumferential weld imperfections was found to influence the buckling behavior of silos and tanks. The influence of a recently developed shape function on the buckling behavior has been examined. The strengthening effect of weld-induced residual stress fields was also studied, and the extent of the increase in buckling strength was derived for a large range of cylinder geometries.