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Wood Frame Shear Wall Hold Down at Masonry Wall 4

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KootK

Structural
Oct 16, 2001
18,574
I've got some wood shear walls coming down on parallel masonry basement walls. I have the following questions:

1) What are some good tie-down connector options for this scenario?

2) Is there anything unusual to be worried about with masonry? I kinda have this picture in my head of the tie down yanking the upper courses of the block away from the rest.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
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Kootk said:
Don't quite know yet. Relatively small. I was hoping to get a handle on the detail and a rough capacity and then work backwards from there to determine how many panels I want.

I have been running into this monthly on my residential jobs now that they are cracking down on lateral stability in our area. Also, 75% of our foundations are 8" CMU.
As has been suggested, I run the rod all the way into the footing. I give them the option of not grouting the cells that contain the rod. This gives them some flexibility in the rod while framing. I usually show a double band in the area of the shearwall so the chord compression loads can easily span over the un-grouted cell column.
 
Thanks for all the help gentlemen.

jayrod said:
Are they not finishing the outside of the gradebeam with some form of insulation/parging etc?

Yes, yes they are.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
@BVSD: I apologize. In the flurry of responses, I missed on of yours and failed to answer a few of your questions.

BVSD said:
Can your anchor rod splice to a footing dowel?

Probably. Currently, I'm digging XR's idea of running the anchor rod all the way down.

BVSD said:
How deep is you masonry "grade beam" - I don't know that I've ever seen a "masonry" grade beam.

Poor terminology on my part. Let's call it a stem wall.

BVSD said:
Is there a concrete footing?

There is. 16"W X 12"H

BVSD said:
Do you have a detail? You usually do!

Yeah, I'm a sketch-a-holic. It's funny. I seem to have oodles of time to post sketches in other peoples threads. Then, when it's my thread, I'm in a hurry for an answer and I just go bare bones. I posted a partial above. If you feel that anything is missing from your mental picture, let me know.



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
Kootk,

One thing worth noting. if you bring your threaded rod into the stem wall and through the top grade beam so you are transferring tension loads into the rebar... make sure you put 90-degree bent bars from the vertical cells into the bond beam. try to only use one bar per cell this way at the laps you only have 2 bar diameters. I've done this numerous times and it works... as far as numbers and construct ability but only for residential so i have never inspected it during construction, TBD.

If you are using straps, you also should consider this. it will keep the bond beam from pulling off due to inadequate laps.
 
Thanks for the tip Eric. I'm gearing up to do a lot of these so coming up with a good preferred detail is key. The design of the foundation is actually not within my scope which makes things a bit awkward. I'm going to be detailing the tar out the stem wall locally but then handing off the design to someone else. Ah well...

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
Oh lord. Delegated foundation design? Are you designing "mobile" structures?

You could just give them the expected tensile load at each location and let them figure it out. Show an intended connection but otherwise stay hands off and cover the details in CYA statements about coordinating connection details. Is this project north or south of the 49?
 
jayrod12 said:
Oh lord. Delegated foundation design? Are you designing "mobile" structures?

Close. Pre-fab.

jayrod12 said:
Is this project north or south of the 49?

South.

jayrod12 said:
You could just give them the expected tensile load at each location and let them figure it out.

Honestly, I'm not sure that there really will be great competence at that end. If I ask them to figure it out, I suspect that they'll either screw it up or just come back and ask me to figure it out later.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
 
Understood. And south of the border you want to tread carefully in terms of letting someone else figure it out anyway. Much better to over detail down there. We're a touch spoiled up here that's for sure.
 
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