RISA's STAAD import was written a long time ago by my good friend Roger. We're talking something like 20+ years ago.

STAAD has had numerous, numerous updates since then. I'm not sure the import routine has been updated for those newer STAAD features. I suspect Floor Load is one of those features that's just not part of the import.

Plates should work though. You might take a look at the log file (which is created whenever RISA imports a STAAD file) that should give you some information about what was successfully imported and what wasn't.

Outside of that (and the documentation), you might have to contact tech support directly. I'm pretty sure they won't be able to answer the question themselves. But, they can have one of the developers import the model while running in debug to see exactly what the program is trying to do with those plate elements.

Thanks Josh. I just went ahead and put in a lot of this manually (within RISA). RISA really doesn't get the Floor Load command. But I was surprised the plates didn't come across.