cold joints in retaining wall

[longhornse]

Question:
I have a horizontal cold joint in a retaining wall. Wall is about 1' thick, 20' long. Do you guys see any potential problem? The cold joint is due to concrete truck being late. NO shear key was put in. Please advise. Thanks.

 

[JAE]

Simply calculate the horizontal shear at the point of the cold joint and check shear friction at that point, using ACI 318 chapter 11, Shear Friction requirements as a guideline. Since the shear plane is now not a monolithic condition, your lambda value is smaller - use the value for that of a roughened surface.

 

[miecz]

JAE - Are you sure that shear friction should be applied to walls and slabs. ACI318 has Articles 11.10 and 11.12 specifically addressing walls and slabs.

Article R11.7.1 says shear friction may be applied where it is considered appropriate to investigate shear transfer across a plane in structural concrete. To me. that means - in structures similar to the cases tested in the research leading to the code provisions. Apparently, the research addressed corbels and precast beam ledges. Do you know if the research tested slabs or walls.

PCA Notes on 318-02 says that shear friction reinforcement should be anchored in confined concrete. It goes on to say that confinement may be provided by column ties, "External" concrete, or special added reinforcement. I don't think slab or wall reinforcement is confined by the PCA definition.

 

[Qshake]

On a macroscopic level and therefore regardless of the stress transfer mechanics, this is an abominable result of something that could have easily been managed properly. It still can be corrected, mind you.

The problem is that an owner would be willing to accept this sort of thing, rather than to reject it as not meeting the standard of care level expected of the industry. If the owner hasn't alredy accepted it without a pay decrease he probably will. And the point: it's not all about the money, will be lost forever.

Here we have something that not only looks like crap but will ultimately leak water and fine soil particles which will wind up staining the wall. Over time as water goes through freeze-thaw cycles (assuming it is such a climate) the cold joint will eventually open up to the point of requiring patch work.

Seems a shame that we have to accept that kind of garbage.



Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[DaveAtkins]

I have always believed shear friction can be used in ANY concrete to concrete interface, and so I agree with JAE.

DaveAtkins

 

[SacreBleu]

I did a lot of study about shear-friction, back in the early 80's. Unless the Code changed (I am not up to speed on the latest ACI), I would not use the ACI equations that are written specifically for "corbel-like" conditions (in agreement with jmiec)