Design and Analysis of Silos for Friction Forces

The effect of axial friction forces on the calculated hoop stress of an unstiffened silo, or of the top unstiffened portion of a silo is analyzed. Ignoring the beam-column interaction between axial friction forces and radial pressure due to the grain may result in an error of 20% in some cases. This results in a variable actual factor of safety which depends on the geometric characteristics of the silo. An instability analysis is carried out which sets limits on the maximum unstiffened length of a silo. This is done on a probabilistic basis and an algorithm is suggested for the design of an unstiffened silo or a silo stiffened by rings.