shear reinforcing at construction joint 1

[ampersand]

I find myself designing a 15'-0" tall, 14" wide concrete retaining wall, which will sit directly on 24" diameter piers, spaced at about 8'-0" o.c. There is an 8000# lateral load, per foot of retaining wall, that I must transfer into the piers.

Naturally, the contractor will pour the piers and the grade beam separately, so there is no shear value from the concrete itself. So, I need to provide some embedded rebar dowels, sticking straight up out of the piers.

I approached this by trying to use ACI equation 11-17, but it basically doesn't allow for the bars for this orientation. I suppose I could call for the bars to be installed at an angle, but it seems unnecessary for this application, for just providing shear transfer at a construction joint. And it looks funny, and I just know that this can work the way I'm thinking...

Of course, I could just calculate the rebar shear strength as As*Fy*0.4, and maintain adequate edge distances and spacings. Is this the right way to go?

Help! And thanks in advance.

 

[JAE]

You should use section 11-17 - Shear Friction in ACI 318.

Specifically use equation 11-25 with the max. value of [φ]Vn as indicated in 11.7.5.

 

[Lion06]

Look at equation 11-25 in 11.7.3.1 (ACI 318-05) for shear friction.

 

[shin25]

Along with transferring shear, don't you have to transfer moment as well thru the joint?

You want to install the bars at an angle, is this to follow the slope of the retaining wall? If so, rather you can install prebent rebars with straight legs in the pier and bent leg sticking out for secondary pour.

While designing the reinforcement, you have to consider the combined effect of shear and bending.