ACI 318 General Questions

[drasticxx]

Hello Guys

1) I am designing according to the ACI code, but I would like to follow the IBC for earthquake zone design instead of ASCE, so my question if I do so which load combinations I should pick, the one based on IBC,or the one based on ASCE(the same as ACI) to make results consistent or it doesn’t matter!!!!

2) I can found in ACI calculation the deflection based on I effective for beams and one way slab, so for two way slab ,where is the reference?

3) They is one statement said that third of flexure reinforcement for T beam can be distributed in b effective and the rest will be in bw( can anyone reference the clause in ACI318-11),I can’t find it!!!

4)0ne important thing is the ACI code is using three words (hoops, stirrups, seismic stirrups),for hoops I found one details in in ACI code for intermediate sway, but what the difference with others

5 Clause 11.2.1.2 Calculate Vc for axial member, so what about combined moment and axial Vc

 

[JAE]

Here's some responses to the first three questions.
1. The IBC refers to ASCE 7 so they should be generally compatible. If they are not - the IBC would generally alter or amend the ASCE 7 spec a bit.

2. There is nothing direct in ACI 318 for two-way deflections other than a table that limits how thin you can go (Chapter 13).

3. I think it is in chapter 10. If not then chapter 7 but I'm away from my office so can't look it up.



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[drasticxx]

Thank you,
any calcification for point 4 and 5

 

[Illbay]

I would also like clarification.

Keep in mind that when you say "The ACI Code" now, it makes quite a lot of difference WHICH version you mean.

For instance ACI 318-14 is quite distinct from ACI 318-11 - or indeed, every other edition of the code previous to it.

 

[drasticxx]

AIC318-11

 

[KootK]

2) I can found in ACI calculation the deflection based on I effective for beams and one way slab, so for two way slab ,where is the reference?

If you're talking lateral deflection, you can use ACI 318-11 10.10.4.1 (0.25 I_gross). That clause references "Flat plates and slabs" and does not distinguish between one and two way systems. I don't know of a code specified effective "I" for vertical deflections.

3) They is one statement said that third of flexure reinforcement for T beam can be distributed in b effective and the rest will be in bw( can anyone reference the clause in ACI318-11),I can’t find it!!!

ACI 318-11 10.6.6 is the only related clause that I'm familiar with.

4)0ne important thing is the ACI code is using three words (hoops, stirrups, seismic stirrups),for hoops I found one details in in ACI code for intermediate sway, but what the difference with others

If you reference specific clauses where these terms are used, we can probably parse out the meaning. In general:

1)Hoops - transverse reinforcing encompassing the entire member and most often used for longitudinal bar buckling prevention.
2)Stirrup - transverse reinforcement that may or may not wrap the entire cross section and are used to resist shear.
3)Seismic stirrups - same as #2 but with 135 degree seismic hooks at the stirrup leg anchorages that perform better than 90 degree hooks when exposed to significant plastic deformation.

5 Clause 11.2.1.2 Calculate Vc for axial member, so what about combined moment and axial Vc

See ACI 318-11 11.2.2.2.


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.

 

[drasticxx]

Thank you