Compression tests on cylinders with circumferential weld depressions

The behavior of thin cylindrical shells under axial compression is very sen sitive to imperfections in the initial geometry. Local axisymmetric imperfe ctions are among the most detrimental and have been shown to be a regular f eature of circumferentially welded joints in civil engineering shell struct ures such as steel silos and tanks. Many of the experiments on which curren t design rules are based were performed on elastic Mylar, copper, or alumin um specimens, which have some very different characteristics to those of st eel shells. Furthermore, very few laboratory tests have ever examined the c onsequences of fabrication processes on shell buckling strength, although t hese strongly influence the amplitudes and forms of geometric imperfections . This paper presents the findings of a careful experimental program on lar ge steel cylinders fabricated with a fully welded circumferential joint. Th orough measurements were made of the initial imperfections and their transf ormation into a buckling mode. The results are compared with elastic-plasti c finite-element predictions and the most recent design standard.