Cantilevered concrete deck with radius

[FSS]

I am designing a 6" concrete deck that will have about a 5' cantilevered radius portion (picture a half-circle cantilever). I am trying to come up with an efficient design and not get carried away with reinforcement. Putting in rebar that follows the radius looks good on paper, but is not very effective at design. A series of varying length bars seems to work better for design, but then I have curved sections without reinforcment at the ends. Maybe a combination of the two is best.

Any recommendations?

 

[MarcbSE]

The cantilevered deck would be a one way slab. Your primary reinforcement for flexure and shear will run parallel to the cantilever. These bars would be varying lengths to extend out to the end of the cantilever.

In the opposite direction you would only have temp & shrinkage reinforcement. The bars could run perpendicular to the main bars.

I would add extra radiused bars at the edge of the deck just to try everything together, and to help with anchorage of any handrails, etc.

 

[jike]

Obviously, the layout of the main bars has to resist the negative bending moment. I assume the maximum moment is along the straight face of the half circle. If that is the case, I would lay the bars out at right angles to that face to effectivly resist the negative bending moment. Provide T & S bars at right angles to the main bars. I probbaly would also add circumferential bars along the outside edge.

 

[csd72]

Just lay bars at right angles sized on the worst cover situation.

Check that the 45 degree resultant of the two bars is enough at the 45 degree mark and then you are okay for strength.

Circumferential bars are a must top and bottom along the outside edge.

Radiused bars are a pain, and IMO never get done right.

csd