When using AECOsim Building Designer's STAAD import tool, all of my Horizontal Braces are imported as Beams. Vertical Braces, however, always seem to import correctly.
STAAD.Pro essentially treats all members as Beams - there are no definitions or categories such Beam, Column or Brace - so it only distinguishes members by their orientation; e.g., horizontal, vertical and sloped. That is why the STAAD Import tool in AECOsim Building Designer only includes mappings for these three orientation options, and why horizontal braces are imported as beams.