Nonlinear buckling of cylindrical steel silos with fabrication cracks

Abstract

Large steel silos are typical kinds of thin-walled structures that are usually constructed with a vertical, circular form and are used as vessels for storing particulate granular solids in the industrial and agricultural sectors. In the present analyses, the buckling behaviours of circular steel silos with circumferential and meridional fabrication cracks are evaluated in accordance with Eurocodes EN1990, 1991, and 1993 [1–6]. A steel silo with a diameter of 10 m and a height of 24 m is used as an example silo. The finite element models of the steel silo cover a wide range of crack geometries: circumferential crack angles ranging from 10° to 60°, meridional crack lengths ranging from 0.5 m to 3.0 m, and various crack heights. The buckling equilibrium paths and buckling deformations are examined through a large number of numerical calculations. The effects of single circumferential crack, single meridional crack, multiple circumferential cracks, multiple meridional cracks and silo slenderness on the buckling behaviours of the silo structures are specifically addressed. The buckling modes of the silo structures with fabrication cracks are completely different from those of a geometrically perfect silo. Circumferential and meridional cracks have substantial influences on the buckling deformations, which occur mainly in the area around the crack. The most unfavourable crack height with respect to structural buckling is located in the lower position of the silo wall, and the buckling load factor increases with the decrease in crack length. Moreover, the cracks are more unfavourable to buckling behaviour of silo structures with larger slenderness than those with smaller slenderness.