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Re: FW: LRFD Load Factors.

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This appears to be a subject that has varying opinions. For what it is worth,
here is mine:

Different cultures will use buildings in different ways. While one may feel it
is OK to put no more than 100 people in an assembly hall and will enforce it to
that standard, another might feel it appropriate to have 300 people or more in
the same room with no enforcement. If the load is adjusted to accomodate this
difference then the load factor will not need to be. However, the load factor
normally accomodates the probability of overload and this can be different where
enforcement is lax and the culture has different traditions.

The phi factor is used to cover variations in material and construction quality.
This definitely varies from country to country. There may be much more variation
in concrete and masonry construction than in steel, but this also depends on
many things. Is the steel imported? What standards does that country have? How
much independent inspection is there on the project? Is there a greater
probability of mistakes  getting hidden or overlooked? Is field welding up to
the same standards as AWS or AISC?

I believe the engineer needs to adjust both the load factors and phi factors to
accomodate those differences outlined above. How that gets done, I am not sure.
This is any area that obviously needs some study.

Jim Kestner, P.E.
Green Bay, Wi.



La Count, Curt wrote:

> I believe that you can use the same LRFD load factors anywhere in the world.
> The factors are not a function of location, but of load.  The local
> jurisdiction will prescribe the intensity of the load to match the perceived
> risk (50 year wind, 10% exceedence in 50 years, ect).
>
> To deal with different materials or load effects, the phi factor is used.
> As long as the material is the same, I don't believe that these would change
> based on location either.
>
> I hope this helps.
>
> Curt La Count, P.E.
> Jacobs Engineering
> Portland, OR
>  ----------
> From: Adolfo Galvez
> To: seaint(--nospam--at)seaint.org
> Subject: LRFD Load Factors.
> Date: Thursday, November 19, 1998 3:37PM
>
> I will appreciate your comments about next topic:
>
> LRFD codes has Load Factors and Resistance Factors. Example AISC,AISI, etc.
>
> Question is:
>
> When you are designing for another place outside USA, do you still use the
> same USA Load Factors in load combinations for Dead, Live, Earthquake and
> Wind?, because Load Factors are function of the statistical data for a load
> type in a determinate geographical area, and maybe using USA factors is not
> in the safe side.
>
> Also, Resistance Factors for steel, concrete, aluminum, etc, are the same?
>
> Maybe a simple and safe approach is to use an ASD code?
>
> Thank You
>
> Adolfo Galvez MSc.
> Lima, Peru.
>