This paper considers the numerical non-linear analysis of the behaviour of the cellular steel beams taking into account the geometrical and physical nonlinearities. Nowadays, the analysis of the cellular steel beams is well investigated. Therefore, it is not difficult to obtain and verify the load bearing capacity values for a member with known dimensions. However, it might be difficult for a known value of applied load to obtain a section with the rational dimensions. The purpose of this paper

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... is to illustrate graphically the different modes of failure for the cellular steel beams investigated, comparing their behaviour under different values of ultimate load for different sections with different modes of failure and stress distribution. In this paper a method is developed for selecting a cellular steel beam section with the rational dimensions and parameters for a known load using finite element analysis and existing software. Therefore, the concept of selection of rational sectional parameters for the steel beams with the multiple openings, based on the data of the numerical analysis carried out, is presented as well. Hence the following conclusions are drawn: 1) It is important to select the rational section dimensions because that would enable the best use of the steel and provides economic solutions; 2) The concept of simple selection of rational section dimensions significantly improves the steelwork design process.