Answer:
If you are using members with cross-sections that are not known by the interface, you should use the conversion file for the cross-sections. This mapping file can be easily filled with the names of the cross-sections. In the left column of the table, write the names of the cross-sections used in TEKLA, and in the right column, write the DLUBAL names or select them from the library.
Please watch the attached video.
Note:
In TEKLA, you have to have the right environment. In the video, Chinese cross-sections should be transferred, so the Chinese environment has to be used in TEKLA.