Bar Around Corner of Cantilever Concrete Retaining Wall

[majbacker]

Would anyone be willing to provide thoughts on the detail below? This is for a cantilever concrete retaining wall. I am trying to show the horizontal bar around a 90 degree corner in the wall. I was going to use the details from CRSI, but I don't think I would have enough development length with hooked bars. These are #4 bars and the wall thickness ranges from 12" to 14".

 

[jdgengineer]

The inside bars should definitely be hooked into the outside layer of steel rather than inside to inside as you have shown.

 

[majbacker]

I am getting an Ldh of 8.5" for a #4 bar. after the bend, I would only have 6" into the wall. It seems like making the wall thicker for just this purpose is kind of crazy. Maybe I am missing something on the required Ldh? It seems like most walls would not have enough development length?

 

[Celt83]

Research Curved Bar Nodes: https://www.concrete.org/publications/internationalconcreteabstractsportal.aspx?m=details&id=19949

For these corners you are really sending the tension around the corner vs developing the bar tension into the corner.

 

[Ron247]

The inside bars should definitely be hooked into the outside layer of steel rather than inside to inside as you have shown.

I agree. You cannot make that inside turn so easily. The inner bars terminate with a 90 degree hook at the outer bars. So, you have 2 separate hooked bars in combination to provide the inner reinforcement.

Draw the actual 90 and 180 degree bends of different rebar sizes to scale and study the outcome. I have seen #8 bars shown going around a corner in a wall but when you draw the bend diameter to scale, the bar starts running out of the wall before it gets to the corner. They cannot bend to a tighter diameter without fear of cracking the bar. The #4s you have are not as bad, but it is a good thing to have in back of your mind.

 

[majbacker]

Research Curved Bar Nodes: https://www.concrete.org/publications/internationalconcreteabstractsportal.aspx?m=details&id=19949

For these corners you are really sending the tension around the corner vs developing the bar tension into the corner.

Research Curved Bar Nodes: https://www.concrete.org/publications/internationalconcreteabstractsportal.aspx?m=details&id=19949

For these corners you are really sending the tension around the corner vs developing the bar tension into the corner.

How would the tension be calculated? I'm not sure there would be much bending or tension in the corner since the wall is already designed to retain the soil as a one way cantilever slab. Not being cute just trying to understand fully.

 

[majbacker]

Here is the updated detail:

 

[KootK]

This is the seminal thread here on this exact topic and I highly recommend reviewing it: Big Bad Retaining Wall Thread

Or is your detail a plan detail where the retaining wall turns a corner in plan? If so, that changes things and there seems to be some confusion here on this. In this case your second detail is better than the original and will be fine without any explicit attention to development length. Somewhat depends on what side the dirt is on.

 

[canwesteng]

If you aren't actually relying on the bending capacity at the corner, then go with the second detail and call it a day, no need to check development length.