Here's another link to a better picture of a "Swing Beam"

http://www.historiclogandtimber.com/timberimages/scotlandbarn4.jpg

I believe the name "Swing beam" was given to the beam so that you could swing a wagon being pulled by a horse around inside the barn.
If a post was there holding up the beam then there wouldn't be enough clearance to swing the wagon around.
But I could be wrong.....

To me, the problem here is the large clear span - 30' and then trying to add a second floor on it. This is an engineering problem. As you go beyond 24 feet, the stresses increase dramatically. I actually have the same problem in that I want a 30 foot clear span and second floor living space above. I haven't gotten deep enough into it yet however.
It sounds like you need to be working with an engineer to determine all of the loads that will be applied, and how much load your frame can support. As is, it probably can't support both the snow and live loads of a second floor, as that is not what it was designed for. So then you have to look at what you can do to increase it's carrying capacity. That will mean moving bents closer together, reducing the width of bays to see if is sufficient to carry the loads. If that's not good, then increased timber size and careful analysis are in order. If it comes to that, your're then going to be building a frame from scratch.

Depends, hay is not light. I do agree about span increasing stress. When a span doubles the bending moment quadruples, the span is double and the load is doubled.

Jim I have heard that as well and seen drawings depicting that, I don't know for sure, these barns typically have a drive through pair of doors, so I don't see the need to turn round, but that sure doesn't make me certain one way or the other.

So you are assuming a hay loft. He said it was a 30 foot clear span and he was PLANNING to add a second floor. To me this implies that it does not or did not have one. It's always in the details...

DonP

if your barn is anything like what is pictured in the links... do not be deterred. this is stronger than anything you could buy.

that beam is strong enough to swing a carriage. look at it.

by the way as you go beyond 1 foot the stress increases dramatically!

decreasing the spacing between bents might be a good idea, maybe not. chances are this was over "designed" based on good carpenter intuition. don't be deterred the live load of a couch, chair, dresser and a couple of people ain't that much.

Nothing can be said until the frame is disclosed....

Thanks folks. I'll try to clarify. I am looking at turning this frame into house. My question around the "code" is exactly what brad_bb mentioned in his post:

"the problem here is the large clear span - 30' and then trying to add a second floor on it. This is an engineering problem. As you go beyond 24 feet, the stresses increase dramatically. I actually have the same problem in that I want a 30 foot clear span and second floor living space above."

I appreciate everyone's input. I'll try to get some additional details in the near future.

well you can do some basic engineering calcs yourself. Although it has withstood the test of time from a snow load perspective I would not put any type of dwelling on a 30' span from what you have stated are beam sizes.

Building codes here in canuckistan state a structue needs to comply to engineering rules. New or used building!

When in doubt buy local....find someone to cut you a frame out west based upon a traditional design. By the time you are done with this project, hauling, erecting and engineering you may just be better off starting from scratch!