huangyhg

ltb of cantilevers to aisc codes
we are currently looking at a design in our office which has been completed using aisc wsd codes (march 2005). we have a query which i was hoping some of the us based 'tippers' might be able to help with. the topic was discussed briefly in 2007 but the links provided no longer work.
should the 2.1 k factor for cantilever columns per table c-c2.1 (asd 9th ed) be used?
i don't think aisc addresses this. my s&j text references the ssrc guide, 5th ed. for k factors, but also says it is conservative to use the actual unbraced length with a cb=1.0 (it goes on to say that this assumption requires that loading be applied at the shear center or at the bottom flange).
if i rember correctly, when checking allowable compressive stress for cantilever, k = 2.0 (or 2.1?).
when designing purely flexural
ussuri,
you may find this cisc publication helpful:
page 32 of the cisc publication is included separately to save you all from plowing through that long document.
best regards,
ba
structuraleit & daveatkins are both correct.
per "steel structures - design and behavior", 2nd ed. p.483, by charles g. salmon & john e. johnson: "...the lateral buckling of a cantilever beam is not even sever as the unbraced segment under uniform moment. since the moment at the end of the cantilever is zero, the compression force in the flange decreses from a maximum at one end to zero at the free end".
it concluded with: "the authors suggest that the actual cantilever length be used...taking kl = l is recommended".

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