ACI 318maximum reinforcement spacing

[jeffhed]

We do not allow any concrete vertical or horizontal reinforcement to be spaced more than 18" o.c. due to the fact that it is listed as the maximum spacing in ACI 318 in multiple places and applications. I am specifically interested in any exceptions to 14.3.5 for vertical and horizontal wall reinforcement. I have a client that is doing an ICF home with a 6" core that he is claiming that he does 24" o.c. spacing all the time. I can't find any exceptions in the code for exceeding the maximum 18" o.c. spacing for walls. Anyone know of any exceptions to the 14.3.5 to space reinforcement farther apart? If not I'll stick to my guns, but he is so adamant, I decided I would do a little more research before telling him I'm not budging.

 

[JAE]

The home perhaps falls under the IRC instead of the IBC and this 318 doesn't apply? Our city code has adopted an amended table to the IRC which replaces the basement wall reinforcing in the IRC with one that has stood for some time. There are many cases where #5 @ 48" o.c. are specified.

 

[jeffhed]

I have looked in the IRC and the ICF tables look like they are going to be able to help me.

Thanks for your help, JAE

 

[adie56]

check the euro code or any other codes they may help ya

 

[ishvaaag]

I remember the classic text of Haas on plates and shells and I remember by then (sixties or seventies) for these thin elements (there and elsewhere) the recommended practice was not to exceed twice the thickness in the separation of mesh rebar. For any ratio of reinforcement this can be attained by reduction of the diameter or the rebar, and at least you know every chunk of concrete has something to which hang. This may seem some horrific thought for the life for some concrete structures but the fall of crowns of vaults is still of concern and I myself have seen both foundations and concrete beam deflections (upon age and creep) of around 5", and about the same where the ratios of the thickness to the span were not properly respected (not precisely a beggar's work, the Ministery of Commerce and Industry in Madrid, Spain). So, the reinforced concrete that started as ferrocement, at closer spaces of wire reinforcement, should to some extent remain so, and it is always better not go for big expanses without reinforcement. Otherwise plank chunks may rain.