Critical assessment of Eurocode approach to stability of metal cylindrical silos with corrugated walls and vertical stiffeners

Economical and Safe Method of Granular Material Storage in Silos in Offshore Port Terminals

“…When properly designed, these silos have twice as high buckling load capacity and twice as small weight as silos made of flat sheets, • analytical dimensioning of silos made of corrugated sheets which is based on present silo standards is too simplified and uneconomical, especially for silos with relatively large distances between columns (it neglects real, three-dimensional operation of the entire structure), and should not be applied, • silos made of corrugated sheets should be designed using the Finite Element Method (FEM), which provides opportunities for more realistic assessment of silo's buckling load capacity, compared to the standard-based calculations. This approach leads to massive material savings, at the same time making it possible to analyse in detail such important phenomena as, for instance, bending of silo columns at the foundation, • the buckling load capacity can be approximately assessed using the modified procedure described in [18], • the granular material in the silo significantly increases its load capacity. The scale of this increase depends on: elasticity of the structure, stiffness of the stored material, and type of flow, among other factors.…”

“…the corrugated sheet stiffens sufficiently the column in the tangent plane to the wall); the column is only loaded with the vertical force applied to its end; the column rests on elastic foundation along its length; the column is pinsupported at its ends; the solution does not depend on column height. The stepwise change of bending stiffness of ribs and jacket can be taken into account in a more detailed analysis, making use of the Finite Element Method (FEM) [17,18,19], for instance. Due to relatively conservative values of buckling load capacities obtained from the model of bar resting on elastic foundation, the reducing effect of imperfections is omitted.…”

“…Simultaneous existence of these two completely different methods to calculate the buckling load capacity (depending on the distance between columns) leads to the discontinuity between them. The difference in buckling load capacity values at the boundary of applicability of these two methods can amount to as much as 700% [18], which testifies to the imperfection of the procedure given in the standard [2]. The results of calculations made using the FEM method [10,[17][18][19] confirm that the approach described in the standard is too conservative, especially for large distances between columns, when the applicable column stability analysis is based on the model of bar resting on elastic foundation.…”

“…The difference in buckling load capacity values at the boundary of applicability of these two methods can amount to as much as 700% [18], which testifies to the imperfection of the procedure given in the standard [2]. The results of calculations made using the FEM method [10,[17][18][19] confirm that the approach described in the standard is too conservative, especially for large distances between columns, when the applicable column stability analysis is based on the model of bar resting on elastic foundation. For some silo geometries characterised by small distances between columns, the standard-based load capacity of a silo without imperfections is nearly twice as low as that calculated using the FEM method.…”

“…The silos with buckling load capacity calculated based on the standards are unnecessarily oversized, by even as much as 2-3 times. The buckling load capacity of a silo made of corrugated sheets and reinforced with columns can be determined correctly using the approach described in [18], which proposes some modifications of the procedure calculating the buckling load capacity for silos with a relatively large distance between columns. The use of this method eliminates the load capacity jump at the applicability boundary.…”