Is it compatible with Blender 2.8? I've placed the Beamng folder into the blender addons folder but nothing turns up in blender preferences.
I haven't personally tried it in 2.80, but more than likely, seeing as all that they changed code wise, it will not work in 2.80 without being updated.
Import jbeam is unfinished feature, you need to manually fix import errors by adding commas to places script except as well as remove stuff it does not recognize, it is very basic sketch of the import feature currently, I'm not sure if it gets more complete, but would be nice if it would. Anyway just look error message and go to your file to line which was mentioned, then try to figure out if there is too many commas, too little or if there is something that just is not well taken by the script like comments or some more advanced jbeam features etc.
Looks to be at line 8 of your .jbeam file where script excepts a comma, so you need to add comma there or funnily enough sometimes you need to remove comma nearby, but try adding comma save file try again, if line changes, keep doing that and it may work. It took quite bit of edits to get semi jbeam imported and I think I had to remove quite bit of stuff from file, so that is bit of trouble, but still it is quite good when one gets import done as editing is quite easy.
No .jbeam will work directly, you need to make tens and tens of edits, reading that line number and what it complains, then edit, try again, see new line number edit again and so on until it imports. Standard hacking procedures.
