shear strength at construction joints
shear strength at construction joints
(OP)
So here's a (hopefully) simple question...
Contractors always want to pour concrete retaining walls in two pours, with a construction joint at the bottom of the wall/top of the footing. If we call for a "construction joint" on our details, are we jutified in assuming that the full shear strength (2*sqrt(f'c)*b*d) can be developed at the joint.
I've heard that this is standard practice, but I can't help but doubt the integrity of these joints.
Thanks in advance...
Contractors always want to pour concrete retaining walls in two pours, with a construction joint at the bottom of the wall/top of the footing. If we call for a "construction joint" on our details, are we jutified in assuming that the full shear strength (2*sqrt(f'c)*b*d) can be developed at the joint.
I've heard that this is standard practice, but I can't help but doubt the integrity of these joints.
Thanks in advance...





RE: shear strength at construction joints
The shear at this joint is carried by shear friction of reinforcing steel passing through the joint and/or a shear key. Personally, I use shear friction and omit the key. I believe there was some discussion of this topic here recently.
Keep in mind that the wall needs to carry the shear at some small distance (say, the thickness of the wall) above the joint. At this location, I use the formula you cited.
RE: shear strength at construction joints
At any rate you should make provisions for a construction Joint at the walls and the footings. Since the concrtet is not continous, you can not use (2*sqrt(f'c)*b*d), Although the othe methods will allow you to transfer shear.