We have as often is thae case with retaining basement walls them designed as one way and in our case 300 mm (11.8 in.) thick. And the vertical reinforcement which is in bot outer and inner face are we and our client in agreement about.
Discussion is requiered horizontal reinforcement. Which for walls acording to ACI should be minimum 0.0020 of the gross concrete area. Now client insist that amount of vertical reinforcement should then be applied in both outer and inner layer. And I say the 0.0020 is for the whole section so when placed in inner and outer layers only 0.0010 times gross area is requiered in each face. Also then the same would apply for one way slabs only that there the ratio is 0.0018. Of course in both cases limitations for maximum rebar spacing.
Am I correct?
Minimum horizontal reinforcement in retaining walls?
(5 posts) (2 voices)-
Posted 8 months ago #
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Great question.
My read of the code is that two layers in both directions are required, EXCEPT with basement walls. Here is the page from ACI 318 on the topic.
So I think for your one-way basement wall, one layer of horizontal bar is okay.
I also find it interesting that ACI requires steel at 18" OC, each direction (14.3.5) as a minimum in any wall, when the IBC allows unreinforced walls. Go figure.
Posted 8 months ago # -
Thanks Tim,
But what about the principle question, which was the real issue.
For a wall or a slab with outer and inner or top and bottom reinforcement, is my understanding that minimum reinforcemnt requierment set by 14.3 or 7.12 is the total reinforcement in the section and not per side, if for one or another reaseon section is with two layers?Posted 8 months ago # -
I'm not sure I understand your question but if it's how much reinforcement per layer, that is addressed in 14.3.4 (clouded section above). The sections just above that specifiy the minimum reinforcement in each direction. Of course this section 14 only pertains to walls.
Posted 8 months ago # -
Maybe the question is so absurd it is difficult to understand. (also m English isn’t perfect) I only wanted some second oppinion to show my clients representative and his colleges (all Egyptians) how wrong they are.
They are convinced that for a wall with a thickness of more than 10 in. where it then is required to have two layers, that each of those layers minimum reinforcement is 0.0020 times the gross area.
They are equally convinced the same principle applies for slabs and footings. And also insist that according to ACI all slabs thicker than 160 mm always have to have reinforcement in both top and bottom. I have not been able to find anything supporting that statement.Posted 8 months ago #
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