Investigation of the buckling behaviour of ring‐stiffened cylindrical shells under axial pressure

Abstract

AbstractTanks and silos are often designed as ring‐stiffened cylindrical shells. Nowadays, the load‐increasing effect of tight ring stiffeners under axial compression has received just little attention in research and practice. Considering the structural safety, the ring‐stiffened shell needs to be estimated on the conservative side in practice. This is not desirable in terms of modern lightweight steel structures. Recently research results based on the numerical studies show that the axial buckling behavior of cylindrical shells can be enhanced by using ring stiffeners. In addition, the analysis of ring‐stiffened structures with numerical calculations demonstrate that cylindrical shells with ring stiffeners under axial pressure are uneconomic according to the current design standard in practice. Therefore, the results guaranteed by experiments are required, before the extensive parametric studies are putted into practice. In this paper, small specimen series are carried out to calibrate numerical models, which are subsequently used in parameter studies, because the large‐scale experiments, in the scale range of e.g. 1: 1 are cost‐intensive and therefore difficult to carry out in the laboratory. Consequently, relative small specimens with the selected radius of 796 mm and thickness 1 mm are tested. The small cylindrical shells are manufactured by welding of two half‐cylindrical shells and the ring stiffeners are spot‐welded to the cylindrical shell. The geometrical imperfection of shells is measured by a 3D scanning technologies. Finally, the experiments by means of geometrically and materially nonlinear analysis with imperfections included are recalculated on the basis of the measured data. The results illustrate that the numerical simulation agrees well with the experimental results.