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Re: LRFD Load Factors.

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Load factors are empirical values derived as a result of experiments, industry experience and other forms of scientific and engineering observations through probabilities of statistics.

They are not cast in concrete but are guides as minimums.

I would look at the design criteria as in the following:

1. Seismic - Zoning, soil classification, fundamental periods and      structure framing.

2. Wind - Zoning, Gust factors, Exposure, Basic Wind Speeds.

3. Gravity Loads - type of usage and application of structure.

For sure, your project would have the fundamental values for wind, soil class and seismic zone. The values you get are often local to the project. The values in various structural design building codes are used as a guide in the absence of data.

As for those data coming from the US (I am not a North American, by the way) or other countries, I would stick to those values because of the strong professional belief that there had been proper modeling for those values to be arrived at. Say wind tunnel test for ASCE 7-95 wind coefficients.

I'd rather go for something that has proofs rather than ride on my gut feel w/c I may have no basis.


______________________________ Reply Separator _________________________________
Subject: LRFD Load Factors.
Author:  MIME:agv(--nospam--at) at INTERNET
Date:    11/19/98 11:52 PM

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.