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Re: aci 318

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The Canadian and US approaches are quite different when using load and
resistance factors. The Canadian code approach is simpler and more consistent
I think. Basically, for ACI 318-95, it is called Ultimate Strength Design and
uses the following (simplified summary):

Important load combinations:
1.4D+1.7L
0.75(1.4D+1.7L+1.7W)
0.9D+1.3W
Plus a few others. For earthquakes, use 1.1E for W where E is a service level
seismic force.

Resistance factors:
Flexure & axial tension=  0.90
Axial compression=        0.70 (can be increased for low axial loads)
Shear & torsion=            0.85 (may be 0.6 for seismic design)
Bearing=                         0.70

Actually, ACI-318 is even more complicated than the above suggests.


David Handy wrote:

> I am trying to correlate results from my Robot software with the Canadian
> code. The Canadian equivalent has not been released yet. The results in
> this case are from ACI 318/95. My questions are as follows:
> Are loads LRFD, and what are the live and dead load factors.
> In terms of strength calcs what are the material reducton factors used.
> I am using the slab or shell element RC design feature.
>
> Canadian code would use:
> live load X 1.5
> dead load x 1.25
> If live reversible then dead x 0.85
> concrete strength x 0.6
> rebar X 0.85
>
> thanks
>
> David Handy, P.Eng
> Ontario, Canada
>