More beam calcs?

[MushCreek]

Anyone up for more beam calculations? I'm not real good with this stuff, so any help would be appreciated. The drawing below represents the floor area under the loft on the barn I'm planning to build. To support the loft, there are the four walls, obviously, plus the 4 posts shown. Side-to-side is 27'; up and down is 30'7". The dimensions between the posts is shown. The plan is to make built-up beams to run up and down, and then put my floor joists cross-ways on top of them. According to the span tables I have, I can get by with 2X8's on 12" centers for the joist material; I'll probably go 2X10. Due to the design of the barn, I need to stay with the 12" spacing on the joists. The question comes in with the beams to support the joists. I'm guessing that 4 2X12's should be plenty, but it's just a guess. I've shown 6X6 posts; will these be sturdy enough at about 12' tall? The loft won't get heavy traffic, but I want to build it for at least 40psf live load.

I guess I have another question, too. If I overlap the joists where they cross the support beams, how do I deal with the 1-1/2" off-set when I put my floor sheathing (plywood) down? Put a filler block in there? Don't overlap them? The floor joists also function as rafter ties, so I thought overlapping them would be stronger. I know the sheathing will also serve to tie them together, but I don't know if the sheathing alone would satisfy the requirement. Thanks for any input!

[Don_P]

I'll be lazy and call the beam span 10'
The joists will span ~7' from wall to beam, half of that is carried by the wall, the other 3.5' is bearing on the beam. Half of the 13' span is bearing on each beam, 6.5'. So trib width is 10'. Multiply it by the 10' beam span and trib area is 100 square feet. assume a 10 lb per square foot dead load plus the 40 pound per square foot live load = 50psf X 100 sf= 5000 lb uniformly distributed load.
Assuming you'll use #2 southern pine, a 3 ply 2x12 or a 4 ply 2x10 passes easily. If you use #1 SYP a 2 ply 2x12 just passes and a 3 ply 2x10 passes by a fair margin.

Lap over the beams and either scab blocking alongside the joist for the remainder of the sheet then shift over to break correctly then scab and shift back. Or adjust the sheet width and lap length to make it work. Remember the problem only happens every 8' not at each joist, so normally I just scab scrap 2x4's to get me through the offending row then shift the sheets back to break.

[Don_P]

Whoops, forgot the posts, this calc should make short work of it;
http://www.windyhilllogworks.com/Calcs/Simple_column.htm
Half the load of 2 beam spans is on each post so ~5000 lbs/post
In #2 SYP you should be fine.

[MushCreek]

Well, you made quick work of that! I was on the right path, but forgot that the wall shares the load on the 7' dimension. It also occurred to me that I will need posts in the walls where the beams terminate as well. I'm going to go 4 courses of split-face block, and then frame from there up, so I better fill the block in that area to handle the point load of the post. I'll pour footings, maybe 2' square under the slab where the posts rest, too. As a toolmaker, there is a tendency to way over-engineer everything, and that's good. It's really embarrassing to get flattened by a building of your own design and construction!

Thanks for the help, Don!