Steel code
For steel structures designed to EC3, member imperfections are intrinsically included in the design routines for all members (beams, columns, braces). Apart from one explicit requirement, carrying out the design is all that is necessary.
The explicit requirement is from Clause 5.3.2 (6) in which member imperfection should be included as part of the analysis when the frame is sway sensitive and the axial force in members with moment connections is above a certain limit. If this situation arises Tekla Structural Designer issues a warning.
Concrete code
For concrete structures designed to EC2, explicit calculations which consider an imperfection effect are carried out as part of the design.
In Tekla Structural Designer this is achieved by adding an additional moment to the analysis results before starting design.