Meridionally Imperfect Cooling Towers

With the recent collapse of a cooling tower in Scotland having been attributed to the presence of imperfections in the positioning of the shell surface, the influences on the linear elastic behavior of axi-symmetric meridional imperfections in cooling tower shells are reassessed. It is shown that even moderate imperfections can result in horizontal membrane tension stresses of similar orders of magnitude as the vertical membrane compression stresses that would exist in the perfect tower. The geometrically imperfect shell is modelled as an assemblage of piecewise continuous second order shells of rotation. The differential system describing the behavior of this shell assemblage is briefly outlined, and a selection of numerical experiments using a finite difference approximation are used to isolate the dominant parameters controlling the response of the imperfect shell.