Cooling Towers with Circumferential Imperfections

The effects of out-of-roundness errors, that cab be introduced durning the construction of cooling tower shells, on the linear stress distributions are examined. Using a simplified, statically equivalent, simulation of nonaxisymmetric geometric imperfections, it is shown that circumferential bending provides the major contribution to the shell’s resistance to the effects arising from these imperfections. It is shown how meridional membrane stresses are also severely affected; this is particularly so if a loss of circumferential moment capacity occurs. The mechanics of behavior in the presence of circumferential imperfections is clarified by a systematic study of the effects of a number of the separate parameters defining the imperfection geometry. As a consequence, suggestions are made as to how the various forms of behavior could be incorporated into future design practice, for the provision of rational tolerance limits for out-of-roundness errors.