Analysis of geometric imperfections in full-scale welded steel silos

The design of metal silo structures is dominated by the need to resist shell buckling failures in service. Shell buckling can occur in many different modes, and the strengths are very sensitive to the form and amplitude of very minor deviations of geometry (geometric imperfections) from the ideal shape. Many imperfection forms have been studied in the theoretical literature on shell buckling, but only one study appears to have ever extensively and rigorously measured the imperfections in real full-scale metal silos: this is the study of the 10,000 tonne Port Kembla grain silos in NSW, Australia. The data from this study of three seemingly identical silos are very extensive and cannot be assimilated without considerable processing. In this paper, the first attempt is made to provide a full characterisation of the imperfection set in a manner that permits them to be used in shell buckling analyses of the silo shell that do not rely on simplifying assumptions.