Wall pressures in squat steel silos from simple finite element analysis

Abstract

Many different procedures for predicting the pressures on circular silo walls have been developed. These include methods based on simple assumptions, plasticity theory, minimising the stored solid recoverable strain energy and some finite element procedures using complex non-linear material characterisation. The purpose of the present paper is to show that comparatively simple finite element techniques which include appropriate wall friction characteristics can accurately model the pressures exerted by stored solids on cylindrical silo walls, at least for the initial filling condition. The study is entirely heuristic in character, and it is not suggested that stored bulk solids are normally in an elastic state. The aim of this development is to study the pressure distributions in squat circular silos and circular silos with flexible walls. Almost all the above-mentioned existing procedures give a poor representation of pressures in squat silos, and only one of them considers silos with flexible walls. However, these two categories are becoming increasingly important as steel silos become cheaper than concrete silos, and as on-ground squat structures replace tower blocks. The finite element analysis presented in this paper is shown to compare well with existing predictions for initial filling pressures in deep stiff-walled silos. Some results are also given to show the effect of wall flexibility on the predicted pressures.