An Equivalent Unique Global and Local Imperfection (sometimes referred as an ‘EUGLI’ imperfection) is an equivalent imperfection that has a shape affine to the form of a critical elastic buckling mode. This design method, in its generalized form designated for the frame structures, is included in the EN 1993-1-1 cl. 5.3.2 (11) since 2002. To this day however, it is neither known in the design practice, nor it is incorporated in the common structural analysis software. This design method is suited for verification of members (beam-columns) with nonuniform cross-section and/or non-uniform axial compressive force. It can be used for general 2D and 3D frame structures. A good example for this complicated structure is an arch bridge. A main problem is that the amplitudes for these imperfections are not experimentally established. Yet a procedure proposed by the same author (as the author of the ‘EUGLI’ imperfection) can be used to obtain a design value of amplitude, which is derived from the substitute member ...