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# CAC Concrete Design Handbook - 4th ed.

## CAC Concrete Design Handbook - 4th ed.

(OP)
Hello all!

I have a question regarding the "Explanatory Notes" in the A23.3-14 Concrete Handbook. I'm designing a plain concrete square footing and section N22.6.6 shows the following calculation for Shear resistance:

Vr = 0.18*λ*Φc√f'c*(lb/Q)

What does the "Q" in the above equation reference here? I do not see any info on this in the handbook. I'm also assuming the "l" and "b" is the length and width of the footing? Thank you.

### RE: CAC Concrete Design Handbook - 4th ed.

#### Quote (FFCrystal13 What does the "Q" in the above equation reference here? I do not see any info on this in the handbook. I'm also assuming the "l" and "b" is the length and width of the footing? Thank you.)

I do not think so ..although i do not have a copy of the CAC Concrete Design Handbook. Assuming the plain concrete section shall be un-cracked section, the subject formula should be derived from famous max . shear stress ( pls look any strength og materials , solid mechanics ..etc ) v= VQ/(I*b).

My opinion is , Q at the Vr = 0.18*λ*Φc√f'c*(lb/Q) is Q is the statical moment of the area, I = moment of inertia , and b is thickness ( in this case width of the ftg)

Just saying ..

Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

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