Cylindrical shells with imperfections

Thin-walled cylinders are used in many engineering applications, including silos, tanks, and containers. They are also widely used in pressure vessels and many other structures in marine, mechanical, and aeronautical engineering. This chapter explains that a cylindrical shell is a highly optimized shape, in the sense that under axial load or lateral pressure it carries loads exclusively by membrane action. The chapter explores changes in stress resultants because of a variety of imperfections affecting cylindrical shells. It reviews some basic aspects of the equations of cylindrical shells that are helpful in interpreting the formulations and results. Models and results for constructional errors that induce geometrical imperfections in cylindrical shells are also presented. The chapter also explains equivalent load methods that can lead to explicit solutions. Silos are also explored in which out-of-circularity and bulge-type imperfections are considered. Furthermore, the chapter presents studies of cylinders with combined imperfections in modulus and in geometry. The chapter concludes that such studies are useful for the simplified modeling of re-inforced concrete problems with smeared cracking.