Stress-----Always refer to service load?
Stress-----Always refer to service load?
(OP)
We know that ACI requires to use LRFD to do design calcs. But now if somebody asks for the shear stress in a reinforced concrete beam, say if we were given 10k dead load + 20k live load, should we use service load 10k+20k to calculate the shear stress or should in the beam we use factored load 1.2*10k+1.6*20k to calculate the shear stress in the beam?
Thanks a lot for your help.
Thanks a lot for your help.






RE: Stress-----Always refer to service load?
The only time you dont factor it is when you check deflection and when you look at the stress of the steel for crack control.
Never, but never question engineer's judgement
RE: Stress-----Always refer to service load?
In lieu of that, I would assume that they would be asking for factored shear stress, given that shear is not a serviceability issue, but a strength issue.
One caveat: if this is a forensic problem, then you'd liekly need to know the actual stresses in the beam (or an approximation of the stresses, anyway).
RE: Stress-----Always refer to service load?
RE: Stress-----Always refer to service load?
RE: Stress-----Always refer to service load?
Thanks a lot.
RE: Stress-----Always refer to service load?
i use factored shear stresses in my cap and footer designs because i have the phi-vc memorized as opposed to the phi-Vc.
RE: Stress-----Always refer to service load?
RE: Stress-----Always refer to service load?
Otherwise, do both and let him pick. But it may make you seem not understand THE ISSUE he has been troubled by.
RE: Stress-----Always refer to service load?
RE: Stress-----Always refer to service load?
I will present this way:
1. Provide unfactored DL & LL, and any other load acting on the beam seperately.
2. List unfactored shear stress (over b*d) for each load case.
By doing so, he can do any combination he wants to, using any load factor he sees fit.
RE: Stress-----Always refer to service load?
Just be clear in your correspondence in describing each.
RE: Stress-----Always refer to service load?