Postbuckling strength design of open thin-walled cylindrical tanks under wind load

Open cylindrical steel tanks for the storage of liquids tend to be rather thin-walled because they are primarily designed for the circumferential tensile stresses from hydrostatic internal pressure. It is desirable to take advantage of the postbuckling strength of the thin cylindrical wall when designing the empty tank against wind load. The theoretical external pressure carrying behaviour of edge-stiffened thin-walled cantilever shells is discussed with regard to both bifurcation and postbuckling phenomena. For experimental verification, a series of postbuckling tests on cylindrical PVC and steel specimens with large radius/thickness ratio (r/t = 2500) under internal underpressure and under a `wind-like' load arrangement has been carried out. Based on the numerical and experimental results, recommendations are put forward for an economic postbuckling strength design strategy. They are compared with existing design rules in tank codes.