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RE: LRFD, ASD, and USD

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{Bill}
It doesn't seem like too many engineers (especially us old geezers) are too
"warm and fuzzy" about LRFD in steel, although I just read a study in Modern
Steel Construction whereby one could save about 15-20% in tonnage when using
Gr. 50 steel and LRFD vs. Gr. 36 steel and ASD.

{john}
What Modern Steel did not mention was the article in Concrete Construction
(concerning composite slabs) mentioning that the concrete volumes go UP even
more than that because of the additional deflection of the Gr. 50 deck and
steel along with the savings from the LRFD method (as compared to ASD).  Now
the slab is thicker and weighs more which considerably bites into their 1.2
Factor.  Oh yeah, they have that strength reduction factor which makes it
ok.  ;)


BTW, the article appeared in the September 1997 issue of Concrete
Construction published by the Aberdeen Group


John Jones
Pell City, AL