L Shaped Cantilever Retaining Wall Bar Development 1

[JoelTXCive]

I have a question regarding L shaped cantilevered retaining walls. I see these walls all the time, and obviously they are not falling down, so I must be missing something.

If you go with an L-shaped wall, then how do you get your flexural toe steel fully developed. It is my understanding that you want the steel fully developed in BOTH directions from the critical section. If you are dealing with an 8" inch wall that has ~2" inch side cover, then you are only left with 6" inches to develop your bars. Even with a hook, that is not a lot of space. (See attached diagram.)

I would think you would need to batter the back wall, or extend a small heel out to provide bar development space?

 

[RickTx]

I'm also curious about this. I'm not the expert here, but can you use corner bars and essentially develop splice lengths in both the wall and the toe. I think another concern with the L-shape wall is developing the wall vertical bars in order to transfer the moment. Typically the vertical bar closest to the front face of wall could bend back towards the heel. I'm interested to see what the experienced pros have to say. Hey, that's my first post

 

[MacGruber22]

http://www.eng-tips.com/viewthread.cfm?qid=401855

"It is imperative Cunth doesn't get his hands on those codes."

 

[hokie66]

That was a good thread, MacGruber22, but it primarily addresses opening joints. The zero heel retaining wall in this thread is a closing joint, which is a less severe problem.

 

[Klitor]

I cant imagine the wall on pic1 having enough sliding resistance.
If it had enough mass to resist it,elements would be thicker and developement would not be a problem.

Edit...didt see its basement...in that case you mostly have top braced or perpendicular walls. If you dont..i would def. Thicken that slab

 

[Klitor]

For wall 2...moments in slab and wall are the same in the corner..no sense to have slab this much thinner.
Possibly have the edge thickened on the underside

 

[MacGruber22]

hokie - good point.

"It is imperative Cunth doesn't get his hands on those codes."

 

[DaveAtkins]

Yes, a bar must be developed on BOTH sides of the critical section. This means you must have a stem wall that is thick enough to allow for full development of the hook--or you must reduce the capacity of the bar.

Now--KootK and I have sparred on whether a bar can be "wrapped around a corner" and develop full fy in both the stem wall and the footing. I have come to believe you can justify this, as long as you don't fail the concrete on the inside of the bend.

DaveAtkins

 

[Teguci]

The bent bar around the corner in a closing joint, unlike the opening joint, stays in tension. Cracking at the joint is initiated under the radius of the bend due to the high compression. Although a
larger, non-standard radius will better distribute these stresses, I think a better strategy is to provide a thickness for both the wall and footing that will accommodate Ldh. I usually use smaller bars at 4 to 6" spacing to keep the thickness of the elements down where possible - also keeps the vertical splice lengths down at the cost of more orange hats.