Anchor Rod Placement

[SperlingPE]

I received a field observation report concerning anchor rods being placed in the following manner:
1. footing excavation is filled with concrete
2. concrete is consolidated mechanically
3. top of footing is smoothed (troweled)
4. anchor rods are pushed into concrete and set to elevation
5. sometimes the stinger is re-inserted into the concrete after the anchor rods are placed.

I have never seen this. My typical experience is that the anchor rods are set to elevation and the concrete is poured around anchor rods and then consolidated.

Is there a problem with the first procedure outlined above?
My thought is that the concrete that is counted on if the anchor rod is subjected to tension is not in place.

Thoughts?

Is there a field test (ASTM) that can be performed to verify anchor rods?

 

[tadeng]

I have a problem with this method of placement. My concern is the same as yours in that the concrete may not consolidate around the anchor rods. I would be even more concerned that the concrete had set up too much if they troweled to top of the footing and then installed the rods.

I have had contractors try to install embed plates in this manner, but not anchor rods (to my knowledge). I would think they would have a more difficult time getting them plumb and at the right height.

 

[JAE]

ACI doesn't recommend this for sure.

I believe in their specifications they even outlaw it.

 

[msquared48]

If these are a holdown for a shear wall - no.

However, if these are #5 or smaller stub bars with 4 to 6 inch bends at the end for a stem wall, I have no problem with the procedure.

However, If the #4 or 5 bsrs are at the end of a concrete shearwall, I would say no there too, as these bars too serve as holddowns.

Mike McCann
MMC Engineering

 

[SperlingPE]

More clarification
These are column anchor rods used to tie column to pad footing.

 

[JAE]

Similar, previous thread: thread507-244716

Also - see ACI 7.5.1 for rebar placement and commentary.

Anchor rods don't exacly equate to rebar, but the principle is the same.

In ACI 301 it states:

2.3.1.10 Place sleeves, inserts, anchors, and embedded items required for adjoining work or for support of adjoining work before concrete placement.

 

[SperlingPE]

JAE that is pretty clear
Now for the field testing/verification

 

[BAretired]

They are likely adequate in shear, but tensile capacity is unreliable.

BA

 

[SperlingPE]

Is there an ASTM field test for this?

 

[boffintech]

Wet-setting of anchors would be fine is the concrete were actually WET. However, the reason Section 2.3.1.10 reads the way it does is because 9 times out of 10 these anchor rods are hammered in AFTER the concrete is very close to reaching or has reached initial set.

Do you really think that on a hot summer day the crew foreman would say something like, "Hey boys, looks like the concrete in this footing has reached initial set. Lets tear it out and start over so that we can wet-set these dowels correctly."

No. It's more like, "Hey boys, the concrete in this footing is getting pretty hard. Somebody hand me the Monday so I can wet-set these anchor rods before that crazy-assed wild-eyed nit-picking inspector gets back."

Note: Monday = 12 pound sledge hammer.

 

[hungnguyen712]

you can have the rods tension tested to see if it'll meet tensile strength requirements. Or just epoxy new rods in.