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Adhesive Concrete Anchors into Construction Joint

Adhesive Concrete Anchors into Construction Joint

Adhesive Concrete Anchors into Construction Joint

(OP)
Is there any issues to consider should an adhesive anchor wind up being located in a construction joint between a wall and a floor?  

RE: Adhesive Concrete Anchors into Construction Joint

I don't think so, if the anchor is in shear.

RE: Adhesive Concrete Anchors into Construction Joint

Screws up your edge distance considerations.  If in tension, not a good idea.

RE: Adhesive Concrete Anchors into Construction Joint

Yes - Probably OK in shear - tension quite doubtful - CALL THE MFG and ASK!!!!!

RE: Adhesive Concrete Anchors into Construction Joint

It you end up relying on the adhesive for tension / withdrawal resistance, expect 1/2 or less of the capacity expected.  As the two sides of the crack move apart, research shows that the adhesive will probably stick to one side and separate from the other.  The result is a reduction on the order of 50%.  For tension, consider undercut anchors and always use values for cracked concrete.

RE: Adhesive Concrete Anchors into Construction Joint

TJ...Assuming you are the engineer on this and a contractor has installed them thusly...

one other consideration...liability.

If you specify the anchor outside the manufacturer's tested parameters, YOU take on the responsibility for the performance.  If the contractor installs it outside your specification and the manufacturer's recommendations HE takes on the responsibility for performance.  

Better HE than YOU!  Write a letter and reject the application...then let the contractor sort out a revision with the manufacturer.  You still get the opportunity to decide yes or no, but it somewhat removes you from the liability stream...at the least it puts you in a boat on the stream, not swimming against the current!

RE: Adhesive Concrete Anchors into Construction Joint

Seems to me that the construction joint will want to expand and conrtract by nature.

The expansion will be locally prevented by the bolt causing spalling, and when the slab contracts, the pullout will be negated and any shear capacity greatly reduced.

Relocate the anchor.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
 

RE: Adhesive Concrete Anchors into Construction Joint

Some of you obviously have a different mind picture of the construction joint than I did.  I didn't think the joint was subject to moving.

RE: Adhesive Concrete Anchors into Construction Joint

OH YES - construction joints move!!!

RE: Adhesive Concrete Anchors into Construction Joint

A construction joint is a straight crack.  Other than the possiblity of shrinkage cracking in the other direction due to  movement parallel to the joint, there should be little difference between installing an anchor in a joint or in any surface subject to cracking.  Assuming the bolt bears on one side of the joint, I don't think there is a problem in shear.  In tension, I don't use adhesive anchors.

RE: Adhesive Concrete Anchors into Construction Joint

(OP)
My concern was hitting a possible cold joint in a concrete wall or column, but I am not even certain that there could even be a cold joint in a column or wall?
Column is roughly 35' tall with a second floor at 20'. It looked like there was possibly a cold joint in the column just above the second floor but I would have thought the column was poured full height before the second floor was poured?

Excuse the extreme ignorance here...I do not work in concrete much other than foundations.  

RE: Adhesive Concrete Anchors into Construction Joint

TJ...yes, there can certainly be a cold joint even if the placement was "continuous".  Continuous to a contractor is "on the same day"!

RE: Adhesive Concrete Anchors into Construction Joint

Toad,
In the normal course of casting concrete structures, there would be a construction joint in the column both above and below the floor.  In other words, the part of the column within the floor depth would be cast with the floor.

RE: Adhesive Concrete Anchors into Construction Joint

(OP)
Well if this is the case, what are your thoughts if the anchors is in a cold joint? Same as in a construction joint?

MiketheEngineer...I absolutely promise you I will call Hilti tomorrow. I swear.  

RE: Adhesive Concrete Anchors into Construction Joint

A construction joint at the column to floor junction is just part of the concrete, same as if cast monolithically.  You don't cast the columns and floor monolithically, because you have to allow the first pour to settle and harden.  If it is only in shear, the anchors should be fine.

A cold joint, not intended?  In a column, it should be treated the same as a construction joint, i.e. the surface clean and rough before casting above, but the problem with that in construction is that the forms have to be removed.  Cold joints in columns should be avoided.  Why do you think you have a cold joint?  

RE: Adhesive Concrete Anchors into Construction Joint

(OP)
It visually  appears that there might be a cold joint, but it could just be a mark left from form work.

Hokie you say "In the normal course of casting concrete structures, there would be a construction joint in the column both above and below the floor"

How far above and below should I expect to see the "construction joint"?
Would this joint be a clean joint or just a cold joint?  

RE: Adhesive Concrete Anchors into Construction Joint

The column should be cast to the slab/beam soffit, then the floor placed, then the column above.  So the construction joint is at the bottom and top of the floor construction.  It is just stacked, not connected to the side like in steel construction.

Clean or cold?  The construction joint should be both.

Yes, what you thought was a cold joint in the column may well be where the formwork butted.

RE: Adhesive Concrete Anchors into Construction Joint

(OP)
I feel like an idiot even talking about this.

I need to hit the books for concrete building construction.
I have never had an opportunity to work with concrete buildings in the firms I have worked for/with or in my own work.
 

RE: Adhesive Concrete Anchors into Construction Joint

Toad, visit the CRSI.org website.  We have some online info, and through the webstore, you can download (FREE) our Tech Notes highlighting things like adhesive anchors, economical concrete designs, and construction practices.  You will have to supply a name and email for the webstore, but the notes are free to download as PDF once you are inside.

RE: Adhesive Concrete Anchors into Construction Joint

(OP)
thanks....will do.
You work for CRSI?

RE: Adhesive Concrete Anchors into Construction Joint

TX...if you are with CRSI...GREAT!  Good resource for the forums.  While proprietary information is discouraged (for obvious reasons), having representatives of technical organizations is a plus for all of us.  Thanks for your input.

Ron

RE: Adhesive Concrete Anchors into Construction Joint

As a trade association (and soon to be ANSI standards development organization), nothing we do is proprietary.  We obviously sell books to fund our activities, but my job with the Institute is to promote the use of reinforced concrete through education and research.  That means giving away the "secrets" to make it easier to design and construct with reinforced concrete.

When looking at concrete anchors, ACI 355 (Anchorage to Concrete) and the Concrete Anchor Manufacturers Association (CAMA) also have good information.

John Turner CSP PE
CRSI Greater Southwestern Regional Manager

RE: Adhesive Concrete Anchors into Construction Joint

John,
Thanks.  Pleased to have you as a resource for the forums.  Your technical input is valued and you have shown that it extends way beyond your CRSI involvement.

Ron

RE: Adhesive Concrete Anchors into Construction Joint

If a crack runs through the hole with the adhesive anchor, the pullout winds up being about half (Nu cracked/Nu = 0.5).  This is for a crack that forms after installation.  This value is not intended to be used where adhesive anchors are installed in existing cracks (who would do that?)  The testing procedure actually cracks the concrete after the anchors are installed.

Ref RILEM - "International Symposium on Connections between Steel and Concrete" - U of Stuttgart

RE: Adhesive Concrete Anchors into Construction Joint

Cracks come in many forms and from many causes.  An adhesive anchor installed into concrete with minor shrinkage cracks which formed at early age and which is restrained by reinforcement would be addressed differently than those installed into a flexural crack due to cyclic loading.

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