steel cylindrical silos, when empty, are susceptible to the crumpling of the sheeting of the cylinder by the wind action. this paper compares the effects of internal and external stiffening with columns on the aerodynamic behavior of cylindrical silos with conical roof. the theoretical studies leaded to wind tunnel experiments, which have been carried out on two types of scaled silo models, one with smooth surface (internal stiffening), the other with ribbed surface (external stiffening), both with two geometric height/diameter ratio of cylinder (0.5 and 1.0) and a conical roof pitch equal to 27o. based on the information gained during these experiments, external coefficients of pressure and drag and lift coefficients are derived for the cylinders, as well as the drag and lift coefficients for the conical roofs. with this, it is identified the best stiffening arrangement for an optimum design of cylindrical silos to resist wind loads. the final result is an updated data set, originated from tests with geometric and aerodynamic characteristics well conditioned, which are applicable to a variety of cylindrical silos.