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Re: LRFD Load Factors.

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> 31                               Message:0031                           31
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> To: seaint(--nospam--at)
> From: Adolfo Galvez <agv(--nospam--at)>
> Subject: t
> 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?

Typically, the load/resistance factors will be balanced to provide a
level of economic efficiency that matches the expectations of the
industry and community for which they were developed (e.g. LRFD was
developed for use within the economic & risk expectations of the US
consumer given a level of construction skill and quality of material
available). Therefore, it may be inappropriate to require the
application of a specific limit states standard in a country other than
that for which it was developed. However, this does not mean that it is
wrong to apply one country's limit states design in another country,
just that it may need to be reviewed.

Load factors are not intended to vary with respect to the statistical
data for a region. Instead, the base load for the region should
accomodate the statistical variability and probability of exceedance.

Resistance factors include the quality of typical workmanship and
commonly available materials, both of which can vary from country to

Canada's design standard load and resistance factors do not match those
in US design standards. The final results may be similar but they may
also be different. Therefore, one cannot conclude that US LRFD is
similar to Canada's Limit States simply because they are both limit
states design standards.

Paul Ransom, P.Eng.           |  Good at what I do
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