web stiffeners

huangyhg

web stiffeners
we have some steel where the fitted stiffeners are 5" away from where we'd like them (in a number of beams, the smallest being a w14). i have been looking through the code to find if there is a criteria for how close the stiffeners should be to the anticpated load.
the stiffeners are for web crippling, and not flange bending, so i was curious as to the allowable distance away. obviously the force distributes throughout the web, so i wasn't sure if there was a limitation on this.
thanks for your help!
rc
all that is necessary for the triumph of evil is that good men do nothing.
    edmund burke

find a job or post a job opening
also, in most of chapter k, they refer to k1.3 thru k1.7 to be checked if compressive load....etc., if i have tension only, then i don't need to check these correct?
thanks!
rc
all that is necessary for the triumph of evil is that good men do nothing.
    edmund burke

how long is the bearing length?  is the stiffener on the bearing surfact at all?
some of the checks are for both tension and compression, and some are just for one of the two.  each section spells out which ones apply.
the bearing surface is located 5" from the stiffeners.
they do not overlap at all.
again this is only for a tensile load. having a stiffener at less than 0.5d away from the load should still help using a 2:1 load distribution, right?
rc
all that is necessary for the triumph of evil is that good men do nothing.
    edmund burke

k1.2 - local flange bending - tension
k1.3 - local web yielding - tension/compression
k1.4 - web crippling - compression
k1.5 - sidesway  web buckling - compression
k1.6 - compression buckling of web - compression
k1.7 - doesn't really apply here.
so only k1.2 and k1.3 apply correct? i did miss k1.3 in my previous post.
what about having stiffeners at a distance away from the load?
thanks.
  
rc
all that is necessary for the triumph of evil is that good men do nothing.
    edmund burke

when you say bearing surface, do you mean hanging surface?  if web crippling is the problem, how is your load in tension?
if you are hanging a load from a plate welded to the flange, the stress will be maximum at the top of the fillet and will be spread over a distance something like n+5k.  the stiffener will not participate if it is outside of that.  also, for tension in the web, a stiffner will not help at all (and maybe even hurt) if it is not welded to the flange.
where are you getting the n+ 5k value?
rc
all that is necessary for the triumph of evil is that good men do nothing.
    edmund burke

n+5k is the distribution length in the aisc code equations for web local yielding, for a load applied greater than d from the   
right, n being the weld size and 5k for further than d from support and 2.5k for less than d. is that in each direction or a 1.25k in each direction?
rc
all that is necessary for the triumph of evil is that good men do nothing.
    edmund burke