Análise estrutural de silos metálicos prismáticos.

Abstract

Last years in Brazil have shown an agricultural growth that has forced several sectors to fít in productive patterns to maintain competitiveness within the process of economic globalization. In this context, agroindustrial product factories, particularly the ones involved with rations, tend to search for new alternatives to favor production and reduce costs without affecting the quality of the final product. Among these alternatives there is the use of vertical silos due to their capacity to facilitate the process of rations production and remove the need for great horizontal warehouses. The mere use o f vertical silos without a previous knowledge of some characteristics such as the most appropriate shape and dimensions for each situation, however, may not produce the desired outcome and can create problems with the flow of products due to inadequate dimensioning of storage cells. Aware of such an insecurity, the present research had the objective to study the tensions produced on the zigzag shaped walls of a 2m x l m prismatic metallic silo, and to compare results found with theories and similar studies. The methodology proposed by BMBH was used to determine the flow properties of pelletized soybean (product used in the experiments). DIN 1055, ISO 11697, EUROCODE 1 and AS 3774 norms were used for the calculation of pressure whilst the simplifíed methods of Ravenet and Troitsky were used to calculate tension. Strain gauges and displacement transducers were used to obtain data concerning the real efforts on the walls. Based on results found it can be said that pelletized soybean presented granular characteristic and that the effort generated on the walls due to its unloading increased according to storage time studied. Concerning the theories studied, it was concluded that either Ravenet theory or Troitskys can be recommended for the design of prismatic silos since they present great accuracy when contrasted with experimental values.