According to the standards (EN 1993-1-1 and EN 1999-1-1) and the clause 5.3.2 (11), it is possible to use the elastic critical buckling mode as an imperfection and determine the amplitude+ of this imperfection. Imperfection is called the Equivalent Unique Global and Local Initial Imperfection (EUGLI imperfection). The whole calculation procedure according to the 2nd order theory with EUGLI imperfection is called the EUGLI method. The whole theoretical background of EUGLI imperfection was published in Chladný & Štujberová 2013; Baláž 2008; Dalemulle 2013; Kovač 2012. Because of the complexity of the solved problem, a computer program was developed in MATLAB programming language (MATHWORKS), which is capable of calculating not only the simple beam structures, but a variety of frame structures as well. Some obstacles in the EUGLI method calculation were discovered, which are the main topic of this paper. The most important formulae described in (EN 1993-1-1 and EN 1999-1-1) clause 5.3.2 (11) is in (1). Symbol ηinit,m,max represents the amplitude of the EUGLI imperfection in the shape of the elastic critical buckling mode


Presented explanations cover only a small part of the whole knowledge about the use of the EUGLI imperfection procedure (EN 1993-1-1 and EN 1999-1-1 clause 5.3.2 (11)). Therefore, for a full understanding of EUGLI imperfection method, it is recommended to study the background in Chladný & Štujberová 2013.