ieff for composite steel beam

huangyhg

ieff for composite steel beam
can someone point me to a reference on how to calculate ieff for a partially composite steel beam?  i can't find anything in s&j or online except for a reference to bs 5950-3).
check out our whitepaper library.
ieff = 0.75iequiv
iequiv = provided as equation c-i3-3 on p16.1-309 of 13th edition (incorrectly noted as ieff).   
thank!!!  that is quite a little gem that was tucked away in the commentary.
willisv, i am not sure that's correct.  what source did you use to decide that iequiv is the quantity computed using eq. c-i3-3?
for what it's worth, my mentor back in grad school is one of the big-name aisc guys and has been teaching steel for 40 years and he uses eq. c-i3-3 in deflection calcs.  of course, that's the way i've been doing it for years too, but it's just because i followed his lead.
also, to further muddy the water, segui uses ieff=0.75itr in one of his example problems (page 580 of the 4th ed.).

271828-
that note about iequiv is in the errata (i did look for that myself).
i noticed ram also uses ieff=iequiv, not 0.75iequiv.  also, my s&j text talks about using 0.33 to 0.5ec when determining itr to account for concrete creep and shrinkage.
ok, perhaps that's correct.
i think segui's method is clearly not correct because it totally leaves out the effect of more or fewer studs.  even ilb in table 3-20 varies depending on sum(qn).