Thru bolt to CMU wall

[Croceng78]

Hi, I have a connection for a steel beam to CMU wall. The connection consists of a steel plate with nelson studs embedded into a CMU wall and a tab plate welded to it in order to attach a steel beam. The contractor missed this connection and now I am planning on having thru bolts with a plate on the other side of the CMU wall. My question is: would I need to specify some epoxy within the (oversized) hole that is drilled into the CMU wall so that there won't be any slip when shear is applied? Is there any information/resources out there that I can look into for this? Thanks in advance for your time.

 

[KootK]

I mostly avoid thru bolting although I do acknowledge that, behaviorally, it must have some merit. I avoid it in situations like this because:

1) As you are finding, robust design guidance for through bolting is difficult to come by. This is the closest thing that I know of and I question its applicability because it speaks to a double shear situation which most of these setups are not: Link.

2) A single shear connection like yours will have the anchors delivering load to the CMU mostly near the face of the wall where the beam ties in. As such, epoxy anchors are likely as effective as through bolts, if no more so. To the extent that the connection puts anchors in tension, I acknowledge that the through bolting -- with a back side plate -- is helpful.

If it's me, I'm skipping the through bolting and trying to make a go of it with HY200 or HY70 screen tube anchors depending on whether you're dealing with solid grouted wall or hollow cells.

 

[dik]

Thanks for the article, Koot...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[Eng16080]

I'm not sure if this is relevant to your situation, but if the connection relies on epoxy and is used to support fire-resistive construction, you may want to look for a different option. Not long ago, I read through the evaluation report for Hilti HIT-HY 200 epoxy and came across this:

Anchors and post-installed reinforcing bars are not permitted to support fire-resistive construction.

I wasn't previously aware of this limitation.

 

[MotorCity]

OP - I've embedded Nelson studs into the top of a wall, but never into the side of a CMU wall. How does one do that, can you share your original detail?