Floor Joist and Beam Uplifts at Three-Point Bearing

[GlulamSam]

I am working on a residential project with an interesting framing layout. What I have is a second floor that does not align with the main floor wall below. I have a large glulam beam that will be "set up" so that it does not drop down below the bottom of the floor joists. I have floor joists for the second floor that hang into the beam on one side. The other side of the beam has a flat patio roof that hangs into it. See the framing layout below.

I am having some issues with two items. The first issue is that the floor joists span approximately 21' feet to the garage bearing wall and then they go an additional 4' to get to the glulam beam. My calculation shows that if the floor joists hang into the glulam beam they will each put a rather large uplift load into the beam. Should I not detail the joists to hang into the beam, but cantilever instead? Should I note that the joists should break at the bearing wall so they aren't continuous joists? My worry with both of these ideas is that I am 100% that any detail or note I put on the plans will not be done correctly. The framers will hang the joists to the beam. If they do that, will that be a major problem later on? Will the floor joists explode out of the hanger and pull the sheathing up? Will nothing happen?

The other item I'm worried about is very similar. If I calculate the large glulam beam to bear in 3 locations then I have a massive uplift at Support 3. I considered designing the beam to cantilever past Support 2 and put a note on the plans telling the framer to NOT bear the beam at Support 3. Again, I am confident that the framers will bear the beam at Support 3. I have an uplift force of 7,000 lbs. in that location if I design the beam to bear there. What will happen if they do indeed bear the beam at Support 3? Will the connection "fail" and then it ends up going back to my cantilever design? Will it pull the floor sheathing and wall up with it?

My calculations show these large uplifts for the floor joists and the beam. What will actually happen in real life if the framers build it how I suspect they will? Would appreciate anyone's experience/knowledge on this topic. Thanks!

 

[BAretired]

How about removing Support 2, B2 and HDR 1? Beam B1 could span 31' from Support 1 to Support 3. Columns could be steel HSS with U-shaped beam supports...a much cleaner framing system.

 

[GlulamSam]

if the beams are the same depth, they must be separated far enough to permit B1 to rotate at Support 2 without forcing B2 to rotate. I don't favor HCA connectors in this case.

I don't see how the HCA would be any different than notching B2 and bearing on top of notched B1. With the notch solution wouldn't any rotation at the end of B1 force B2 upwards just like it would with the HCA?

How about removing Support 2

Support 2 is the exterior wall of the home. I can design the beam to span all the way from Support 1 to Support 3, but the fact is that it will rest on Support 2 which will effectively make Support 2 a bearing point when the beam is loaded.

 

[Aesur]

Split and stagger the I-joist at the wall is the simplest solution and commonly done. You can't control what they do in the field without requiring observations which is extremely rare, but you can at least have it properly documented on your drawings.

If this is truly a header (lower than the beams) then use a Simpson CC type post cap on a stub post, or if height allows directly attached on the beam, this should in most cases easily provide the bearing capacities you need, however be careful of bearing perp to grain calculations. If the beam is at the same elevation as the header, then hang the beams from the header (I know this isn't your case since you are spanning over, just throwing it out there for information).

If you don't want two different sized beams there, then use the same depth beam but split them. If they aren't split you could be looking at larger columns and additional concrete for uplift or bearing, splitting and adding a 20 dollar post cap is probably the simplest solution considering construction time and cost of concrete that may be needed.

 

[BAretired]

I don't see how the HCA would be any different than notching B2 and bearing on top of notched B1. With the notch solution wouldn't any rotation at the end of B1 force B2 upwards just like it would with the HCA?

With the HCA hanger, the top of B1 and B2 are tied together; if the bottom of B2 bears hard against B1 the beams are rigidly tied together, separated by vertical distance H. It is not a hinged connection.

With a simple notch, B1 is free to rotate without forcing B2 to rotate.

 

[BAretired]

Support 2 is the exterior wall of the home. I can design the beam to span all the way from Support 1 to Support 3, but the fact is that it will rest on Support 2 which will effectively make Support 2 a bearing point when the beam is loaded.

I have not seen the architectural drawings, but Support 2 would not exist if it was simply removed. I don't like a 31'-0" span either, but 26'-0" isn't much better. A more sensible column spacing would be better, but the architect must approve.

If you are considering large drift loads outside the wall, the large span may not be possible.