reinforcement design in two way slab
reinforcement design in two way slab
(OP)
can top and bottom bars both be used when cecking for shear?
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reinforcement design in two way slab
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RE: reinforcement design in two way slab
RE: reinforcement design in two way slab
BA
RE: reinforcement design in two way slab
Mike McCann
MMC Engineering
RE: reinforcement design in two way slab
BA
RE: reinforcement design in two way slab
RE: reinforcement design in two way slab
Furthermore there is the "general" applicability of the shear-friction theory, that also involves (or solves) the case of shearing action along an interface, but has wide range application such support of slabs on walls or design of composite studs.
Not to name the shear action itself on the rebar, one can see it drawn in the Paulay book, main rebar distorted in shear in a cracked section. Our codes have taught us to remain far from such thoughts, but surely we are still applying some of this stuff in distilled form when designing anchors.
RE: reinforcement design in two way slab
I will have to check my copy of ACI tomorrow but Australian codes do not include any contribution from tensile reinforcement (even though it does help), it is a function of the concrete shear strength, shear area and any effective prestress.
RE: reinforcement design in two way slab
I am sure they do include it.
abe123,
You only include the tension steel.
Since you are asking this question then I recommend that you do some reading on concrete shear in order to understand the subject. The ACI commentary as well as a good text book will help.
Here is a good start:
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As engineers we not only have to know, we also have to understand.
RE: reinforcement design in two way slab
When in doubt, just take the next small step.
RE: reinforcement design in two way slab
RE: reinforcement design in two way slab
You are missing (a little) something. For beam shear, see Paragraph 11.2.2.1, Equation 11-5. This contains a factor based on the amount of tensile reinforcement. It doesn't help much, but the provision is there. This is in ACI318-08, not sure about earlier versions.
RE: reinforcement design in two way slab
RE: reinforcement design in two way slab
After I read it I remembered about the "more detailed analysis", I just always use the basic 2rootf'c.
RE: reinforcement design in two way slab
I am calculating equipment use on the two way slab, to check for shear on the point load city engineer had objection that I can not use the bottom bars in calculation;
RE: reinforcement design in two way slab
RE: reinforcement design in two way slab
RE: reinforcement design in two way slab
Beam shear has a component that includes the reinforcement ratio [Ast/(b*d)] in the shear capacity of the concrete alone, this must be tensile steel, so depending on whether the top or bottom bars are the tensile reinforcement than this reinforcement is used in the calcs but under no circumstances can you sum both top and bottom reinforcement