Hinged Residential Wall - Stability Issue?

[ANE91]

Saw a fun one this weekend. Background: 20-year-old residential structure.

Sketch attached. For tall walls like this, I normally see buckled studs / inadequately fastened sheathing. I've never seen a hinge develop like this. Coolest bit was that, north of this condition, there was a floor diaphragm completely preventing this mechanism.

Anyway, I'm tasked with "fixing" it. Short of rebuilding the wall, I'm entertaining two ideas.

1. Thick-gauge CFS straps straddling the hinge, on the outboard face of the wall. I don't like this solution. They're for tension (e.g., uplift), usually, and don't have much bending stiffness. If this wall continues to kick out, then I don't believe the straps will do much.
2. Inboard waler beam — maybe a WT. I don't much like this solution, either. Gaps at the flange will need to be shimmed/grouted, and we'd be relying on that puny sole-plate-to-stem-wall strap in the load path. Additionally, potential buckling of the WT stem may render this solution cost prohibitive.

I'll keep noodling on this. Hoping for some smarter answers while I dust off my stability textbook. Thanks.

 

[SWComposites]

Seems like you need to first determine the cause of the displacement.
Confirm the footing is intact and not rotated.
Confirm the stem wall is intact.
Is there a gap between the slab and stem wall?

 

[jhnblgr]

How about some photos of the failure?
This wall should be studs 12” in depth likely engineered lumber. Joints should be lapped for splicing to transfer bending.

 

[phamENG]

That is odd. I agree that deeper investigation of the footing is warranted. This is a pretty typical detail - the stem wall is short enough that you should get enough fixity to prevent failure at that hinge.

To truly repair this, shoring of the roof and stud wall and partial (if not complete) rebuilding of the stem wall to ensure it's sufficiently fixed is probably the play.

This wall should be studs 12” in depth likely engineered lumber.

Huh? Why on earth would you need 12" engineered lumber studs for a 14' wall with nothing but roof load?

 

[XR250]

Huh? Why on earth would you need 12" engineered lumber studs for a 14' wall with nothing but roof load?

jhnbldr seems to be on an engineered studs kick lately
I ran into one of these yesterday but it is an area with known plastic clay soils so it usually means the footing rotated. These are built all the time in my area - usually without issues.

 

[GaStruct]

Based on the info you provided, this wall/ftg is overturning. 26" of unbalanced backfill won't always work with the typical foundation details depending on soil and surcharge. Is this a garage?

I would excavate the exterior to see what is going on with the footing. It it's probably undersized for overturning. I've seen just the wall used as a footing before for small structures like this.

Possible solution would be to locally demo on the interior and post install helical piles bracketed to the footing at "x" spacing designed for the uplift.

You may even be able to simply pour another footing on the exterior and anchor it to the existing toe. This would add some weight and shift the CG to stop the overturning.

 

[jhnblgr]

His drawing has the height at 32ft, unless he meant length. Wind load deflection and stiffness to prevent cracking of finish.

 

[phamENG]

Looks like 14' to me.

 

[jhnblgr]

 

[jhnblgr]

Must be my phone

 

[EngDM]

Must be my phone

The 32ft appears to be the extent of wall that is hinging, into the page.

 

[SE2607]

I agree with the consensus in that I believe this is a footing rotation problem. To verify, I recommend excavating enough to determine the footing dimensions. Also, it should be verified that the slab is doweled into the footing. Is there a separation between the S.OG. and the stem?

I don't think straps are going to fix the problem.

 

[jerseyshore]

Gotta be a foundation issue if it's not a garage impact-related problem.

This detail is used on nearly every garage I've ever seen so it is probably a combination of everything that can go wrong did: eccentric loading, small or no footing, minimal anchorage, hollow block, etc. Maybe no rafter ties or some extra thrust at roof level too.

 

[DoubleStud]

Either foundation issue or roof thrust issue. What is the roof? Maybe scissor trusses that have too much horizontal deflection?

 

[XR250]

Either foundation issue or roof thrust issue. What is the roof? Maybe scissor trusses that have too much horizontal deflection?

How is the roof thrust making its way to the foundation? Unless there is a moment connection between the top of the wall and the roof framing, this can't happen.

 

[DoubleStud]

How is the roof thrust making its way to the foundation? Unless there is a moment connection between the top of the wall and the roof framing, this can't happen.

maybe you are right. I was looking at it backward and perhaps the measurement of the 1" was from the top of the wall.

 

[ANE91]

Is there a separation between the S.OG. and the stem?

Big time. I left a lot out because this is not a diagnostics query, but I greatly appreciate the musings. That’s why I love this forum. While I agree that the best fixes are produced when the cause is known to some degree of precision, what can I say; clients are cheap / unwilling to satisfy my curiosity. It’s also not a great mystery. Only so many mechanisms can do this.

Is this a garage?

Yep. Just your standard, run-of-the-mill garage. One of the nicer ones I’ve seen, though. Too bad it’s hinged.

 

[BAretired]

You need to consider the entire cross section, not just the part shown. It is possible that the entire structure is unstable.

With pins as shown below, getting rid of pins B and F does not make the frame stable, unless you are relying on the roof as a diaphragm.

 

[GaStruct]

Not sure I follow this. Racking isn't the cause of the hinge and I don't see a feasible way of making F and B fixed.

In light frame construction, F and B are always pins. In this case, the foundation is a cantilevered retaining wall. If this was built correctly, a wall that tall should have a dowel which will create fixity at G. Rendering this structure stable from SOG surcharge loads and WW & LW wind. Hence why I believe the hinge to be caused by overturning.

However, this is separate from the structure not racking because the roof diaphragm spans to the gable walls. If G is a true pin, the wall will hinge but the structure still wouldn't rack.

 

[BAretired]

Photographs might be of some help in understanding the problem, particularly a photo of the framing.