It is most likely that Solidworks use a different Section property catalog than STAAD.Pro. Any section which is not available in the standard section database of STAAD.Pro will not be identified by the program. It is better if you import the 3D DXF file generated in Solidworks in STAAD.Pro first and then assign the section in STAAD. If the section is not available in STAAD Section database, you can manually add the section in the database by providing the section name and property values.
For more information on import files in STAAD, you can go through the following post--
communities.bentley.com/.../9234
For more information on import files in STAAD, you can go through the following post--
communities.bentley.com/.../9234
