Hi Allan
Great work with the curved members.
I found a new site whit BIM-objects
http://www.reedconstructiondata.com/ that you can look in to this is a firm in state of Georgia USA.
You can convert them with a DWF to DWG/DWX converter, Goggle dwf converter, but of some reason x and y axle have change places so the object lying down but that is easy corrected in TFP by set X-axle to 90 deg use custom scale I have used 1:100 but I'm not sure this is correct scale. Ther is a free dwf viewer Autodesk Design Review 2010 from Autodesk that you can dowload.
Robert