aisc fillet encroachmen
 

aisc fillet encroachment
all,
can i frame a beam (tw = 3/8") into a column (w8x31) at its web using a double clip (2)-l4x3x5/16 (long leg back-to-back) with the use of figure 10-4, lrfd third edition or figure 10-3, thirteenth edition? according to this figure k=6.125", tf=0.435, kdet - tf = 0.69 thus encr. = 1/4". this leaves me with k+2(encr)=6.625". any thoughts?
tia
i'm a little confused on your nomenclature. i'll have to make an assumption:
the 6.125" dimension that you call "k" seems to be a misnomer. it's closer to a t dimension, but that's the t dimension for the w8x28 and w8x24, not the 31.
the quick way to do this stackup is to add 6" (2-3" angle flanges) to your tw of the beam coming in. in your case this would be 6 3/8". then compare that to the t dimension for the column you're framing into. the t for a w8x31 is 5 3/4", so it won't fit. note that it also will not fit in a w8x28 or w8x24 either.
sorry, t not k. i disagree with your statement. for a w8x31 t+2*encr = 6.25" thus providing you a 1/4" web thickness. for a w8x28 or w8x24 t+2*encr = 6.5" thus providing you a 1/2" web thickness. your assumption is correct based on older aisc versions but without newer references listed above you struggle to understand my issue.
i have my 13th lrfd/asd sitting open right here and every number i wrote on the earlier post checks out.
i was not taking advantage of what's called "riding the fillet". you do indeed get an extra 1/2" of space for this
as a followu-p to swearingen - further information for "riding the fillet" can be found on p10-8 of the 3rd ed, lrfd along with a table of allowable encroachments.