CMU Wall Removal

[TRAK.Structural]

I have a potential project where the client wants to remove a portion of a CMU wall that separates different areas of an industrial building. The CMU wall is part of the lateral system for each side of the building so I am envisioning using either steel moment frames (or braced frames if I can convince them) in place of the wall in the final condition. The tricky part is that the upper portion of wall is going to remain. See my sketches below for the current condition and the proposed new condition. Design of the shoring and sequencing of the work will be up to the contractor but obviously I would have to come up with something that can indeed be built. Does this look reasonable? What pitfalls am I not thinking of?

 

[RPGs]

Seems reasonable. Personally, I've never seen shear studs used as you show them, but of course that doesn't mean it isn't done, or it wouldn't work. I imagine it'd be quite difficult to install and inspect. I'd potentially look at post-installing anchors to the side of the CMU course, fastened to the beam flange with an angle or similar. I think that would give me a better feeling about it if I could get it to work--easier to inspect at a minimum--but that's just me.

 

[jerseyshore]

Seems reasonable. Personally, I've never seen shear studs used as you show them, but of course that doesn't mean it isn't done, or it wouldn't work. I imagine it'd be quite difficult to install and inspect. I'd potentially look at post-installing anchors to the side of the CMU course, fastened to the beam flange with an angle or similar. I think that would give me a better feeling about it if I could get it to work--easier to inspect at a minimum--but that's just me.

I agree. Anytime we have a retrofit we always try to use Hilti's into the side of the block.

OP how big is this opening going to be? And how long is the overall length of wall?

 

[SWComposites]

is there a concern with creating a "hinge" at the top of the new moment frame?

 

[TRAK.Structural]

I agree. Anytime we have a retrofit we always try to use Hilti's into the side of the block.

OP how big is this opening going to be? And how long is the overall length of wall?

I think the height of the opening will be about 15 feet. The client wants to remove basically the entire length of wall (around 100 feet).

is there a concern with creating a "hinge" at the top of the new moment frame?

Initially my gut says that the diaphragm connection to the low roof will brace the wall/frame at that level. I could possibly brace the steel to the low roof structure with some kickers.

 

[SWComposites]

If the sketch is ~to scale, that little angle connecting the low roof to the wall looks rather wimpy. Kickers sound like a good idea.

 

[TRAK.Structural]

The angle at each roof is continuous. It will engage the diaphragm, kickers still may be justified though.