Rebar schedules for box culverts

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Joel_graff
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Re: Rebar schedules for box culverts

Postby Joel_graff » Sun May 06, 2018 10:25 pm

thschrader wrote:
Sun May 06, 2018 4:18 pm
The culverts are prefabricated in a factory and then delivered to the construction site.
Is that right? If so, why not connect the V/U/H-rebars to get one rebar?
Whats the minimum concrete cover you must use in USA?
regards Thomas
Taking a quick look at your example, I'd say that economics governed that design. Looking at the rebar layout, they took one large rebar and reduced it to four, consisting of two unique shapes. I'd argue that it's probably cheaper to do it that way. If that's a cast-in-place design, then that definitely seems like a likely explanation. But even with a precast design, I could see it making economic sense.

So far as structural integrity goes, because the segments overlap with other nearby bars, any negative impact on it's ability to withstand moments in those areas is likely negligible. Further, culverts are generally statically loaded (at least from the sides), and if there's enough fill, the dynamic load from traffic on the road is probably not particularly large. In any case, we tend to over-design our culverts - essentially analyzing them as bridges, so I suspect that the same has happened here...

To be honest, though, I really have no idea. I've not done culvert design for 15 years. But it's probably a reasonable take on the real explanation. :)

To your second question, we go for 2" - 3" of cover, depending on the slab thickness and size of rebar, IIRC...