How to add longitudinal torsional reinforcement to longitudinal flexural reinforcement in beams? 1

[Tstruct]

ACI 318-19 CLAUSE 9.5.4.3 reads:
Longitudinal and transverse reinforcement required for torsion shall be added to that required for the Vu, Mu, and Pu that act in combination with the torsion.

Also in commentary it says to add longitudinal torsional reinforcement to longitudinal flexural reinforcement in beams. Here I am talking about longitudinal torsion only.
My question is do I have to add the whole amount of torsional reinforcement to the flexural? I mean both top and bottom.

For example:
As required flexural (bottom)= 0.9 in.sq
As required flexural (top)= 0.7 in.sq
As required long. Torsional= 0.8 in.sq

Should I provide 0.9+0.8=1.7 in.sq in bottom and,
0.7+0.8= 1.5 in.sq in top?
Or is there anything I am missing?
Also, are side bars required for torsion? If yes, What is the criteria?

 

[JAE]

No - you would place your top and bottom reinforcement where they belong - then ADD the torsional amount, spacing it around the cross section as evenly as possible.

 

[Lomarandil]

So in using the example numbers, one simple solution (for most beam dimensions) would be to provide
0.9+0.4=1.3 square inches in the bottom, and
0.7+0.3=1.0 square inches in the top

 

[Tstruct]

@JAE It looks logical but is there any reference for even distribution? And this even distribution includes sides of beam too?

 

[slickdeals]

You calculate your top and bottom reinforcement, then calculate your additional longitudinal rebar for torsion. For example, you needed 8 in2 for torsion, you would divide it equally on 4 sides (or proportion based on beam depth width ratios). If you had 4#9 top and bottom already, one way to do it would be to provide 2 in2 of torsional rebar on top and bottom by adding an extra 2#9 and then providing say 3#8 on each side face.

 

[JAE]

Look at ACI 318 - section 9.5.4.3 (I'm in the 318R-14 version). Also the commentary.

 

[Celt83]

Also see section 9.7.5.1 in ACI 318-14/19 which notes that the Torsional reinforcement should be distributed around the perimeter of the closed stirrups with at least one bar in each corner and spaced not more than 12". Section 9.7.5.2 also dictates a minimum bar diameter.

 

[Tstruct]

@Celt83 9.7.5.1 , thanks this is what I was looking for.

Thank you everyone for your responses. You all have been really helpful like always.