Comparative study of finite element analysis of steel silos with rectangular and I stiffeners

Silos are used by a wide range of industries to store bulk solids in quantities ranging from a few tones to hundreds or thousands of tones. They can be constructed of steel or reinforced concrete. Steel bins range from heavily stiffened flat plate structures to efficient unstiffened shell structures. They can be closed or open. They are subjected to many different static and dynamic loading conditions, mainly due to the unique characteristics of stored materials. Wind and earthquake load often undermine the stability of the silos. A steel silo with and without stiffeners is adopted and static structural analysis and dynamic analysis is done. The analysis is done by idealizing geometry, material and boundary conditions. Keywords: steel, reinforced concrete, silos.

Necessary Height of the Vertical Stiffeners in Steel Silos on Discrete Supports with Accounting of Imperfections

To ensure unloading of the whole amount of stored product by gravity, the steel silos are often placed on supporting frame structure. The values of stresses in the joints between the thin shell and supporting frame elements are extremely high. It can cause local loss of stability in the shell. To prevent it, many designers place stiffening elements above the supports. Here the question is how high should be the stiffening elements? The appropriate solution is that they should rise to that level till which the values of meridional normal stresses above the supports and in the middle between them are equalized. But where is this level? Many researchers worked on values and ways of distribution of normal meridional stresses above the supports of the cylindrical shells. As a result of their efforts are determined critical height Hcr of the shell and the ideal position HI of intermediate stiffening ring. But these heights are considerably different between each other. To which of them our vertical stiffening elements should achieve? Considering the nonlinear behaviour of the steel, the effects of changes in geometry during loading and imperfections caused by welding works, the author tried to obtain an answer to this question.

STOCHASTIC CALCULATION OF A QUASI-HOMOGENEOUS BOLTED JOINTS OF THE BODY SHEETS OF THE STEEL SILOS

This paper deals with the study of reliability of quasi-homogeneous bolted joints of the body of thin-walled constructions ofthe steel silos. Heterogeneity of this unit can be caused by number of reasons, in particular by presence of bolts of differentstrength in joint. In such case the reliability of the system is determined trough the probability of trouble-free work of the coefficient of the critical factor. The general conception of stochastic calculation consists in using the Monte-Karlo simulationprocedure for the samples of random values of the large volume. It was formed the system of conditions, under which the reliability of joints is provided and analytical expressions for the value of coefficient of the critical factor is got, and also madepractical calculation example with the following graphic presentation on a special coordinate plane – a critical stochasticscale. It was illustrated that random presence of bolts of less strength in field joint rapidly increases the risk of refusal.

Arch effect in silos on discrete supports - Is it a myth or reality?

Steel silos are interesting, complicated facilities. In order to assure its complete emptying by gravity they are often placed on supporting frame structure above the ground. Values of stresses in joints between thin walled shell and supporting frame elements are very high. It can cause the local buckling in the shell. The simplest way to design steel silos is to divide hypothetically the cylindrical shell into two parts - ring beam, supported in some points and shell above, uniformly supported. This conception is accepted by European Standard EN 1993-4-1. The particular moment is that the ring beam and cylindrical body above it are separated. Actually the two elements are jointed and work together in the same time. Considering the last results of Zeybek, Topkaya and Rotter from 2019, and as well as his own research, the author asks the question if it is true that the transferring of discrete base reactions to the cylindrical body is done by bending work of the ring beam, which is the conception in EN 1993-4-1? Or the vertical reaction forces are actually redistributed on the height based on the work of the cylindrical shell under compression as an arch. Using the contemporary capabilities of the programs for spatial analysis of building structures the author will try to find the answer of this question.