Failure Criteria for Shells on Local Brackets

Several criteria are given in design standards for determining the failure load of cylindrical shell structures. When the loading is nonuniform, a nonlinear finite element analysis is required to capture fully the deformation characteristics of the shell and to obtain a true estimate of the failure load. However, even if a fully nonlinear analysis is performed, the determination of the strength of the shell is not always easily achievable. Several different forms of nonlinear load-deformation behaviour are found. The adequacy of existing design guidelines for obtaining an estimate of the design strength is examined. For certain types of behaviour alternative methods are suggested that may provide a more definitive measure. The numerical results are based on silos supported locally on brackets. The results are, however, more widely applicable to shells under a general set of loads. The bracket-supported silo is used in the calculations as it provides a good example of a simple design, but with a relatively complex pattern of deformations leading to a highly nonuniform stress state.