reinforced concrete arches

[mike20793]

Does anyone have any references for design of reinforced concrete arches? They aren't arch bridges, just some relatively shorter span (<15 ft) concrete arches spanning over storefront and picking up some CMU above. Thanks.

 

[robyengIT]

hope it can help

 

[dhengr]

Mike20793:
The above tabulation of formulas is a good start. Then get out your Design of Concrete Structures textbook and go to it. Depending on the details and the makeup of the CMU wall above and around the arches, you might make that masonry above act like a reinforced deep beam. The masonry also has some natural arching ability of its own, providing there is enough wall around and beyond it to pick up the arch thrusts. The conc. arch thrust becomes a fairly big issue and generally requires some tension ties at the found. level, or enough wall beyond the arch to distribute the thrust. You want some added cover on the bot. tension rebars and plenty of closed shear ties, because there is a significant tendency for the tension stl. to pull out of the bot. face of the arch, due to radial forces.

 

[KootK]

Do both the top and bottom surfaces of the concrete take on the arched profile? Or is the top level?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[mike20793]

Both top and bottom take the arch profile and is tied into the CMU above, which will have to be cut (not very precisely along a radius I assume). I'm just working on a deferred submittal and I'm not the EOR and, based on the drawings, the EOR is going to have a tough time resolving the thrust. And of course, no detail showing how the arch ties into the piers, so I'll have to design that, too.

There's not a ton of load coming down on them, so I don't think strength of the arches is a concern, they just have some very narrow piers supporting the arches, but the backup structure isn't my responsibility.

 

[KootK]

I've done a couple of precast arches but, really, never found a good concrete specific reference.

There's not a ton of load coming down on them, so I don't think strength of the arches is a concern

I wouldn't imagine, particularly once the masonry is in place. If there's anything to be concerned about, I suspect it would be arch buckling under a partial load case during the installation of the masonry. I'm assuming that the arch will essentially be used as formwork for the masonry.

I'm just working on a deferred submittal and I'm not the EOR and, based on the drawings, the EOR is going to have a tough time resolving the thrust. And of course, no detail showing how the arch ties into the piers, so I'll have to design that, too.

With the masonry in place, it'll be quite difficult to keep the wall assembly from attracting base building shear. Obviously, I don't know your particular details but that is the scenario that I imagine. That could make the pier connections even tougher. Hopefully you're working with reasonable EOR supplied loads at least.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[mike20793]

Hopefully you're working with reasonable EOR supplied loads at least.

I wish. These are actually the worst set of drawings I have ever seen. It's a combined arch/engineering firm, and by the looks of it, they lack basic engineering judgement.