Burying Steel Beams in Wood Stud Wall Volumes 7

[KootK]

I've got an architect wanting to hide some 30' steel beams inside a 2x6 stud wall system. This tends to restrict the pool off off the shelf W-beams that would be workable.

In what can only be described as an egregious tactical blunder, I mouthed off that even a 5.5" beam flange cannot be hidden in a 2x6 stud wall cavity unless one is willing to allow the walls to move to suit the in place beam locations when one considers tolerance issues such as permissible column misplacement and lateral beam sweep.

In response, the architect would now like me to stick to 4" wide beams to allow for the tolerances that I mentioned. So, yeah, that did not go as planned. Many of the beams would wind up having to be custom fabricated sections which would likely wind up having even worse sweep than rolled beams as a result of the welding heat introduced.

My question is this: is the normal thing to do in these situations to allow the beams to be 5.5" wide and just adapt the architectural system locations to suit? Put the walls wherever the beams wind up laterally? I feel that is indeed the case but I'm not positive.

 

[phamENG]

jerseyshore - you're making me rethink all of the derogatory comments I've made about the Jersey Shore.

KootK - sorry for helping to steer this thread down a very peculiar rabbit hole. What's the verdict on the beam in the wall?

 

[jerseyshore]

The Jersey Shore is the greatest piece of American reality TV ever recorded and I will not stand for any slander so I appreciate that.

I too am curious of the result because I feel like fitting beams in spaces they don't actually fit in is 85% of a structural engineers job.

 

[CANPRO]

Many of the beams would wind up having to be custom fabricated sections which would likely wind up having even worse sweep than rolled beams as a result of the welding heat introduced.

I wouldn't be overly concerned about that. A reasonably competent fabricator should be able to weld a built-up wide flange beam without excessive sweep. If both sides of the web are welded simultaneously or at least sequenced strategically, you should balance the distortion. You're more likely to get decent camber develop than sweep.

Is it just the bottom flange that is a restricted width? If you have some flexibility in the top flange width (and assuming that is the only compression flange) maybe you can make the top flange wider/stockier and help with stability.

 

[HouseBoy]

OK... I'm curious about this question coming from KootK. Something about the post seems off. I hope all is going well.

One thing I would wonder about is the load perpendicular to the wall. Presumably that would be wind load (maybe unless it is an interior wall. Might need a square tube at the bottom flange just to deal with that (especially at the narrower widths. If they need a steel beam, then I suspect it's a long span (even more critical for deflection concerns).

Anyway, My experience is that they would ordinarily pad the wall out to accommodate the width/tolerance (as others have indicated).

Not sure how strict (and why) they need/want to be with the wall thickness.

 

[XR250]

OK... I'm curious about this question coming from KootK. Something about the post seems off. I hope all is going well.

What seems off to me is that he has not followed up.

 

[BridgeSmith]

I wouldn't be overly concerned about that. A reasonably competent fabricator should be able to weld a built-up wide flange beam without excessive sweep. If both sides of the web are welded simultaneously or at least sequenced strategically, you should balance the distortion. You're more likely to get decent camber develop than sweep.

For welded plate beams, the flange to web welds are typically done top and bottom on one side of the web, and then it's flipped over to do the welds on the other side of the web. Any heat induced distortion is very small. As long as the flanges are cut straight when they're stripped from the plate, the beam will be straight. The vertical profile (camber, sag, etc.) will be whatever shape the web plate is cut to.

 

[jayrod12]

What seems off to me is that he has not followed up

Agreed. I followed up with him off board. I'll see if he's just been too busy to follow up. I know I've spent far less time lately on here than normal. Work's been insanely busy.

 

[CANPRO]

For welded plate beams, the flange to web welds are typically done top and bottom on one side of the web, and then it's flipped over to do the welds on the other side of the web.

Depends on the size of the beam/girder, and the fabricator of course. Where I work, for a beam 30" deep, we'd be welding the single flange to web with simultaneous welds. If it was an 8ft deep plate girder, we'd likely do as you suggest. I agree that even in this scenario the weld distortion would be minimal - consider also that the weld is located near the neutral axis of the section which helps.

 

[Brad805]

It is bike season. I suspect our chatty fella is balancing all his interests.

 

[BridgeSmith]

Where I work, for a beam 30" deep, we'd be welding the single flange to web with simultaneous welds.

Interesting; I didn't know that welding both sides of the web simultaneously was feasible. We've had plate girders fabricated with webs as small as 24", but I haven't had the opportunity to observe the fabrication of those. What welding process do you use? Ours are done with submerged arc; it makes very nice looking welds.

 

[CANPRO]

BridgeSmith, sub-arc here as well. If you have dual heads on your welding gantry you can position one on each side of the web. I tried to find a video of that in action, but this is the closest I could get:

https://www.youtube.com/watch?v=qoOlVj-9FSQ

They're running dual heads but on opposite sides of the box section. Same idea with welding both sides of the web at the same time, just different positioning.

 

[BridgeSmith]

Thanks CANPRO. The process I observed was somewhat more low-tech. The whole machine was set up on a cart that rolled down the web. On each side (top and bottom of web), there were (in order) feelers, preheat torches, flux dispensers, wire welder, and a vacuum to suck up and recycle the unmelted flux.

 

[TheDW]

I have been showing W16x31's inside 2x6 walls for years and haven't gotten any complaints. If they're struggling to hide it, they aren't struggling enough to call us about it.

 

[HouseBoy]

" I have been showing W16x31's inside 2x6 walls for years..."
Me too but I use them as columns in walls.
Will be interested to see what comes of this.

 

[Craig_H]

If there is lateral sweep in the beams, could the beam not be pulled into alignment as it's being fastened to the floor framing above? A beam no wider than 5-1/2" should be pretty noodley.

 

[BridgeSmith]

If there is lateral sweep in the beams, could the beam not be pulled into alignment as it's being fastened to the floor framing above? A beam no wider than 5-1/2" should be pretty noodley.

To correct a sweep of about a 1/4", you'd only need to apply 100 lbs at midspan, but even that might be hard to accomplish.

 

[Craig_H]

Hard to accomplish? Two nails will carry that easily, and considering that you likely have floor joists every 16" resting on the beam, I would say it shouldn't be too difficult. Install beam, build floor above tacking joists into the beam's nailer temporarily, then use a come-along to pull the beam into alignment before permanently fastening the floor to the beam and nailer above.

 

[XR250]

Install beam, build floor above tacking joists into the beam's nailer temporarily, then use a come-along to pull the beam into alignment before permanently fastening the floor to the beam and nailer above.

How do you take care of bottom flange sweep?

 

[Craig_H]

How do you take care of bottom flange sweep?

Can't say that I've seen this done, so I should be clear that I am totally conceptualizing here. Bottom flange sweep is what is critical here (top flange will probably be within the drywall thickness of the ceiling), so you could probably "tune" the beam alignment such that the bottom flange is as close to aligned as possible. One could also throw a handful of stiffeners on the beam if they were really worried, forcing the top and bottom flanges into alignment.

Seems to me that there are enough solutions to deal with beam sweep that a good contractor could easily figure it out. Sure, this is picky and expensive, but that's the architect's fault for setting unrealistic expectations for what a wood framed building with 2x6 walls can look like.

 

[BridgeSmith]

Hard to accomplish? Two nails will carry that easily...use a come-along to pull the beam into alignment before permanently fastening the floor to the beam and nailer above.

It could be that easy, but not knowing anything about the rest of the structure, I have no idea about access, adequate anchor points for the come-along, etc. needed to apply the force.