TB, I am familiar with the frame type you speak of. In all of the ones I have seen in the Hudson Valley, the queen post arrangement is not acting as a truss, but transferring vertical load. I have occasionaly seen braces to the outside of the queen posts going down to the ends of the tie beam, which could help make it act like a truss. I think I have seen this in newer barns though where the queen post tie was omitted to accomodate a hay track, (there goes the truss action.) Usually the interior bents have a center post too. Some times in carriage barns, one bent doesn't have a center post and instead has an oversized tie beam going full width. This was so the carriage could be pulled in and turned (swung)around. The huge tie beam in this case is called a swing beam. Some of the old mill buildings in the area have real timber queen post trusses to provide column-free space below. There is one on Columbia Street in Hudson that has an attic or third floor supported by the bottom of the truss, a second floor that is hung by rods from the trusss and a totaly column free first floor.
Best regards,
Chris
