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AISC k values for wide flanges

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In Table 1-1 of the AISC LRFD 3rd edition, k values for wide flanges are
now listed both as decimals and fractions. For example, W16x26 shows
both 0.747" and 1-1/16" for the k value. W 14x90 shows 1.31" and 2". In
every case the decimal value is less, sometimes by quite a bit.  My
first question is this: why are the values so different?  

Second question: Since the values are so different, when is it
appropriate to use the fractional value and when is it appropriate to
use the decimal value?  I was going through the example on p. 14-18 of
the manual, and I checked the R1 value used in checking local web
yielding. (The R1 values are in Table 9-5, not 9-6 as it says on p.
14-18 by the way). Using Eq. K1-3 on p. 16.1-72, I back-calculated R1
for W18x50 and found out that it is based on the FRACTIONAL value of k,
not the decimal value as I would have thought.  However, later on p.
14-18, when the beam flange thickness is being checked, the DECIMAL
value of k is used.

Bonus question (not related to k values): in the example on p. 5-13,
about 3/4 of the way down the page, where the shear yielding design
strength of a W18x40 is being checked, shouldn't there be a 0.6 factor
in the equation for Vn, as shown in Eq. F2-1 on p. 16.1-35?

Rick Burch 
Columbia, SC

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