CMU Vertical Expansion Joint 2

[LearningAlways]

Hello All,

I am working on a shaft wall made of masonry, it bears on a double tee flange. One side of this wall is a vertical drop, top of this wall is 7" from a double tee stem; this means there is no practical access to the top of the wall - very tight space on one side and a sheer drop on the other.

Vertical deflection of the double tee flange is required, thus I need to create a connection that allows vertical movement but that creates a simple span in the out-of-plane axis of the wall. At work we typically use two L-angles drilled vertically into the double tee flange and fit snugly against the wall to allow for this movement. However, based on where this wall is located this is not an option.

I've come across smooth dowels that might solve this problem. They are typically used in slab-on-grade to allow for horizontal movement. We would have to drill through the double tee flange, grease or sleeve one end of the dowel and grout the cells from there.

This is an option but I am seeking other options as well. One that works easily for actual construction of the CMU wall.

Attached is a quick detail. More details if requested.

 

[GC_Hopi]

I would check out hohmann & barnard for cmu accessories Link. Attached are a few ideas

 

[JAE]

Is there a reason you are extending the flange into the wall? Why can't the wall continue past the flange tip and then use a vertical slip connection fastened to the flange top or flange bottom?



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[LearningAlways]

GC_Hopi thanks for the link. I'll take a look.

JAE: The shaft wall bears on the first level double tee. We can't bear on the first level double tee because the shaft wall serves 9 stories of building, the double tee flange can't withstand that a wall that height.

 

[JAE]

You'd better check with your precaster as those flanges are sometimes only 2 1/2" thick.

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[bob33]

Another possibility might be to use a modified version of your typical detail. Use a bent plate in place of of the outer clip angle and fasten it to the top of the tee's flange. It may be necessary to grind down the corner of the flange to accommodate the radius bend in the plate. Build the wall tight to the outer plate and then add the inner clip angle.

 

[hokie66]

"The shaft wall bears on the first level double tee. We can't bear on the first level double tee..." Which is it?

Supporting a masonry wall on the end of a flange of a double tee is a terrible idea.

 

[LearningAlways]

Bob33 would the CMU team be able to build the wall tight to a plate? Sounds great in theory but can they be that accurate?

JAE33 we are the Precast team. Our flange can support the weight of a masonry wall in this case because it is only cantilevered 18". If we need to we'll add reinforcing. Normally we have the benefit of flange-to-flange connections but I can see your concern in this case.

hokie66 that was a bit misleading on my part, sorry. It should read "The shaft wall would have to bear on the first level double tee but we can't bear on the first level double tee...".

Let's assume that the flange is okay and the wall configuration is what it is, any other input on how to make this happen?

 

[JAE]

So just making sure I understand.
This is a shaft - i.e. a square or rectangular masonry "tower" of sorts but on one side of this shaft it is supported by each floor's double tees?
What about the orthogonal shaft walls? Are they also supported at each level by double tees and if so, do they also have a horizontal "gap" joint?
Are you dragging lateral building shear into the shaft at each level?

As far as your dowel joint idea - that looks possible depending on lateral shear, etc.

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[GC_Hopi]

I was reading the thread and realized I never attached my sketch. It should be attached now

 

[bob33]

Masonry walls can be built very accurately when necessary. In the case where the stem is 7" from the wall, it might be necessary to build the wall from the shaft side in which case the clip angle would the installed first and the bent plate last.

 

[kipfoot]

I agree with hokie66's sentiment, but here's another idea similar to GC_Hopi's thought.