Concrete Ultimate Limit States
Concrete Ultimate Limit States
(OP)
I have a concrete deadman reference using the following formula for area of steel:
As = M / 1.44 d
M = moment(ft-k)
d = section depth(inch)
Where the 1.44 comes from is not explained. Not being familiar with ultimate design, is this a common coefficient?
Thanks.
As = M / 1.44 d
M = moment(ft-k)
d = section depth(inch)
Where the 1.44 comes from is not explained. Not being familiar with ultimate design, is this a common coefficient?
Thanks.






RE: Concrete Ultimate Limit States
As=Mu/4d
where:
As=steel area, in^2
Mu=factored moment, k-ft
d=rebar depth, in
You can derive this by assuming the internal moment arm (d-a/2) is 0.9d and fy is 60 ksi in the following equation:
Mu=0.9*As*fy*(d-a/2)/12
That said, I would strongly advise against using any equations you don't understand. Especially if you are "not familiar with ultimate design".
RE: Concrete Ultimate Limit States
These equations are approximate and are good for quick checks or estimations. With the calculator and computer power we have available to us I recommend always just using proper equations. At least understand the assumptions that went into your two quick equations and verify them at the end.
RE: Concrete Ultimate Limit States
I'm just trying to make sense of someone's previous work.
I appreciate your replies.