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Precast Sandwich Panel - Adhesive Anchor Repair

Precast Sandwich Panel - Adhesive Anchor Repair

Precast Sandwich Panel - Adhesive Anchor Repair


I am designing a repair for a precast concrete manufacturing company where a cast in embed plate was left out during production.
The panel composition is 4" concrete wythe - 4" EPS insulation - 4" concrete wythe (total 12" precast panel).
Panel is designed as a composite panel with wythe ties @ 16" O.C. each direction, prestressing strands running horizontally, mild steel running vertically, and WWF in both wythes.

The embed that was left out during production was a cast in embed, which was responsible for supporting a field installed continuous angle (welded to embed plate). The previous embed was responsible for transferring 8k of shear (ultimate Vu).

From attached photos, clouded embed was left out during production.

My question is in regards to the design repair, I am thinking about using a drill and epoxy repair such as Hilti HY 200 epoxy, but how does this type of repair interact with the insulation?
Should I try to justify the forces within the first 4" wythe, with less than 4" embedment? Or can I embed said anchor through first wythe, through insulation, and grab onto back wythe concrete?
I am running some numbers in Hilti Profis Engineering Software and I am not sure if I can say I have a 12" panel, 8", or something in-between.

Or should I go with some kind of wedge or screw anchor? If I go this route should I attempt to grab onto back wythe of concrete by drilling through front wythe and insulation?

Previous detail with the cast in embed is attached also:

Any advice would be greatly appreciated.


RE: Precast Sandwich Panel - Adhesive Anchor Repair

From detail show above, the concrete is thickened to accommodate the embed plate. If this is the case, you have a much better chance for success on repair. I would drill and grout weldable anchor, place plate with predrilled holes, and weld the plate to the anchors.

RE: Precast Sandwich Panel - Adhesive Anchor Repair

Thanks for the reply. Since this embed was missed from production, it is likely the insulation was not held back as shown in the above detail. So I have to assume a 4-4-4 section is present at this location. Unless I had the precaster drill some pilot/test holes to check, I suppose that could be an option.

RE: Precast Sandwich Panel - Adhesive Anchor Repair

I would insist on the precaster verifying the thickness conditions, so you know what you are designing around. I would go by the detail until told otherwise, (or just guess at everything?). I would also want him to locate all of the vert. rebars, so I can miss them too, as much as possible. GPR equipment should take care of that. I would make the new ‘embed’ pls. 12” wide so I can maybe move them a couple inches laterally w.r.t. the vert. rebars and still have them meet about the same spacing on the face of the panel. The 8k shear must translate to some shear per foot of wall, and I’d up that a bit, and design for it, with due consideration for my potential lateral adjustment needs, and load concentrations. I would weld a 2x3 or 3x3 angle 8 or 10” long (maybe just a ½” by 2 or 3” bar stock, to minimize the standoff from the face of the panel) on the back of the new ‘embed’ pl., intended to fit into a grouted, saw cut slot in the face of the wall panel. Then, the drilled and epoxied A.B’s. are really only there to hold the new ‘embed’ pl. to the wall, not to take the primary loading. The epoxy tends to creep under constant full loading, so it’s not a good choice for that type of application. Insist on inspection and quality during the saw cutting and epoxying operations so you know they are done well.

RE: Precast Sandwich Panel - Adhesive Anchor Repair

One thing may make you feel better, as the missing plate is only responsible for no more than 50% load carried by a typical internal plate. Will this help your calculation in making up the strength?

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