Post Installed Anchorage Lap/Fix
Post Installed Anchorage Lap/Fix
(OP)
We've got a CMU core that is being used as a major lateral element on our project. Our detail shows a lapped dowel between the CMU wall and a concrete stemwall below. Unfortunately the contractor missed this detail and are looking for a post-installed fix.
Being that the wall reinf is working hard in the CMU walls above, we were working with some heavy (#7) vertical reinf. We'll obviously have a hard time fully developing the strength of the wall vertical reinforcing with an drill/epoxy installation in the top of a 10" concrete wall.
Thinking our solution could potentially lie in one of the following?
Any and all thoughts/input would be appreciated!
Being that the wall reinf is working hard in the CMU walls above, we were working with some heavy (#7) vertical reinf. We'll obviously have a hard time fully developing the strength of the wall vertical reinforcing with an drill/epoxy installation in the top of a 10" concrete wall.
Thinking our solution could potentially lie in one of the following?
- Unsure if we have the ability to drill/epoxy a "lap" to the vertical reinforcing in the wall below?
- Unsure if we have the ability to core/grout a "lap" to the vertical reinforcing in the wall below?
- Design the drilled/epoxy anchors for the actual design load of the wall reinf above. Ensure concrete wall reinforcing below is sufficient enough to transfer load out of that epoxy failure cone and into the reinforcing?
- Design the epoxy anchors to transfer shear load, install some sort of exterior strap/plate to transfer the tension load (via shear)?
Any and all thoughts/input would be appreciated!
RE: Post Installed Anchorage Lap/Fix
I think you can create a "lap" with the bars in the wall below, but be prepared to drill pretty darn deep and wrestle with the "we've never had to do it that way" criticism.
RE: Post Installed Anchorage Lap/Fix
RE: Post Installed Anchorage Lap/Fix
RE: Post Installed Anchorage Lap/Fix
In addition to that option, I'd propose hydro demolishing the tops of the stem walls down 8", so that you can get mechanical couplers on the bars, and the building the walls back up with repair material. I feel that this might be economically competitive with the drill & adhesive solution. More importantly, to me, is that I feel as though so much drilling, so deep, is going to beat the heck out of your wall. If you're working the core this hard in flexural tension, then you're working your zones similarly hard in flexural compression. I worry that your wall will wind up splitting apart like barrel staves when that happens as a result of internal cracking developing from all of the closely spaced drilling. I don't know how realistic such a failure really is but it's the picture that pops into my head. It's not as though this is something that Hilti will be considering.
RE: Post Installed Anchorage Lap/Fix
RE: Post Installed Anchorage Lap/Fix
RE: Post Installed Anchorage Lap/Fix
No, I believe that they are showing the horizontal bars simply because they complete the strut and tie model implied by the offset lap splice condition. Such bars would surely help with vertical cracks oriented perpendicular to the wall but they wouldn't do anything for the the through thickness cracking that moderately concerns me. Maybe you just agree to have some dowels installed and pull tested over 4' length of wall to see how it goes before you commit to the whole thing.