Rebar Detailing in Curved Structure

[ScratchyFilm]

I am working on a niche structure that is segmented for a total change of 60-degrees in about 30'. I am trying to place spacing of the rebar at 12", but I'm curious how one would place this rebar WITHOUT exceeding 12" on the outside part of the structure.
The attached image in Plan View is what I am proposing to do in order to not exceed 12" (with 12" spacing being maintained on the outside). What is a typical practice for something like this? I haven't been able to find any resources for something like this.

Thanks!

 

[rowingengineer]

What is the structure, makes a difference from sog to foundation to suspend slab.

 

[dik]

I generally don't 'crank' the rebar, but use straight bars with a suitable lap at the ends, and would 'fan' the radial bars.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[ScratchyFilm]

The structure is like a junction box that will connect into a precast box culvert.

Thanks for the feedback dik, I was thinking the same thing about keeping them straight and overlapping. When you refer to "fanning", would you keep the 12" spacing on that outside edge and then have those bars basically all intersect at the same point on the inside edge?

 

[dik]

best to 'fan', and not 'crank'...


yup... and maybe 8" or 10" centres on the inner curve...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KootK]

This would be my recommendation. If there's a contractor to consult with regarding their preference, all the better.

 

[dik]

Transverse bars as KootK and for simple span stuff, I often do this

with the end bar spacing at 2x s... most economical... have to check with design and also allows latitude for slightly different 'spans'. For continuous one-way slabs, I do this:

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[r13]

This the way we usually do. Sometimes you will need more than one short bar in between the full length bars.

 

[dik]

by overlapping the rebar, you have some adjustment... not with continuous bars...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

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Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KootK]

with the end bar spacing at 2x s...

That's slick. For the circumferential bars, this would be a bit less sexy but doable in 10'-ish segments. It may be less costly than radiused bars but, perhaps, harder to place.

 

[KootK]

That's an interesting approach r13. It could probably also be tweaked to incorporate some of the benefits of the other suggestions.

 

[dik]

I'd do something like (curved bars work, too):

I worked for RJC for about a decade, and at the time (I assume they're still great), they were one of the better reinforced concrete engineering consultants in Canada.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[r13]

No, the space will be in between Smax and Smin. You can calculate it out use the circumstance at the point of interest divide by the number of spaces.

 

[KootK]

I worked for RJC for about a decade, and at the time (I assume they're still great)....

Me too. They are still great but, if I had to pick Canada's top concrete team, I'd probably go with Glotman Simpson in Vancouver.

Most of my solutions have been geared toward setting out the circumferential bars in such a way that inference is minimized and structural depth is maintained. It may well be that the circumferential bars are really little more than T&S. If that's the case then structural depth will be less important and other options involving layering may become more attractive.

 

[WARose]

I don't know if this is useful or not....but the few times I have done reinforced concrete arches, I just took cross sections of the arch and called out the flexural steel and stirrup spacing there. The shop (rebar) drawings sorted out the rest. IIRC I did call out a max/min on stirrup spacing realizing the circumference issues.