Answer:
To create an imperfection based on a mode shape, the Add-On “Structural Stability” is required.
After the critical mode shape has been determined in the ultimate limit state using the Add-On “Structural Stability”, it must first be copied to the “Load Combinations”. Only then can the mode shape be assigned as an imperfection using the following options:
"New Imperfection Case"
"Buckling Mode Shape"
The procedure is described in the video.
