Cast in Place Culvert 5

[structuralaggie]

Some civil punk came up with this great idea to burry a culvert 60+ feet below finish grade and it was left up to me to design it. No big deal, I got the loads from the geotech and designed it. It looks more like a bomb shelter than a culvert, and would probably work as one too, unless it is the monsoon season. This thing is stout and heavily reinforced, but I have not put any sort of expansion or control joints in it. I really think it is fine, just let it crack. Since this is my first culvert to design, I was just wondering if anyone else has designed one of these things and if control joints are typically used. Thanks.

 

[cvg]

Con-Arch is worth checking out. Here's the link

http://www.con-arch.com/

 

[mitchelon]

jmiec,

Why would water leak through random cracks and not through cracks at contraction joints?

 

[structuralaggie]

civilperson - Reading parts of chap. 11 of ACI 318, it looks like at best 6sqrtf'chd. Also,ACI 318 11.10.5 says only 2sqrtf'c hd for walls anyway. I am going to have to look into how they can get such high values.

 

[miecz]

Mitchelon-

A waterstop is located in the control joint.

 

[cvg]

I think with proper design and placement of the reinforcing steel to minimize shrinkage cracking and with limits to the length of pour of say 50' - it should be possible to limit the cracking to a minimum, at least enough to prevent excessive entry of water through the cracks. If concerned with differential settlement, control joints can be used as recommended and a properly designed waterstop will prevent water entry. As recommended, a circular or arch shaped structure may be more economical. 120" pipe has nearly the same cross sectional area and would provide similar conveyance capacity, without the need for cast in place, control joints, waterstops etc. which might be a considerable savings if you can get this with the proper D-load.

 

[Qshake]

jmiec -

I like your reference to ACI 350. I think it is more applicable to above ground structures or underground structures that carry contanminants though. Either way, it clearly shows your looking at other resources.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[mitchelon]

waterstop heh, touche, touche.

 

[miecz]

Qshake-

I think of a culvert as an environmental structure. In any case, ACI 350 is very concerned with preventing leaks through concrete, while ACI 318 is not. I don't know of a better reference for this situation.