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allowable load for a w 6 x 25 i beam set weak axis. please

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发表于 2009-9-7 10:59:50 | 显示全部楼层 |阅读模式
allowable load for a w 6 x 25 i beam set weak axis. please.
i have a situation where two structural engineers differ on the allowable load on a i beam. this beam was set in my house on the side as an h allowing a 2x10 rim joist, for 12鈥?oc cj, to be bolted to one of the flanges. above is a bedroom (40 lbs/sf) and roof (19 lbs/sf)span is 13鈥?鈥?supporting one end of 2x10 ceiling joists spanning also13 feet. other end of cjs supported by exterior wall. one engineer said it is fine the other said remove it. i will err on the side of caution and have the beam placed the right way, but was wondering if there is a table or if someone can help me with the maximum allowable load on a beam like the one described set on its side? thank you for any light you can bestow upon me.

did either engineer give you a reason for their conclusion?  was their decision based on the strength of the beam or the deflection?  
running some quick numbers on what you posted, it seems to be ok in weak axis bending and deflection.  i agree with ctw, however - have them support their answers.  if one provides you with detailed calcs and the other just says, "look at it - it's obvious", you'll know who to go with...
did the engineer tell you what to replace it with?  did you actually hire two different engineers? why?  if you actualy hired each, then ask for calculations, or some explanation.  if calculations were not included in the fee then you may see a charge for doing so.  
we cannot tell you who is right or wrong over the internet.
ctw - one said it is too brittle on its side.
swearingen - i will talk to them this morning, thanks
ucfse - this proble was uncovered during a remodel, one engineer was hired the other is a friend that actually did the calcs before the engineer of record and while the engineer of record was out of town, so we can know how to proceed with the remodel. i think that the engineer of record may have felt his feet being stepped on and maybe came up with diff calcs??
'brittle?' correct me if i'm wrong but isn't whether something is brittle (and ductile) dependent on the material.  it is the property of the material which means it fractures without plastic deformation.  hence the orientation of the   
i have doubts about the engineer who said "it is too brittle on its side".  even choice of words can reflect an engineer's competency.
i agree.  the word brittle is almost never used with reference to steel, and certainly not for the situation you describe.
daveatkins
is the beam made of cast iron? if so, cast iron is very brittle for structural applications depending on the carbon content if any. however, i agree with the posts above that the point is irrelevant with regards to orientation of the beam.
bingo!  it looks like we have a winner.  brittle?  w6x25 is a steel designation, although you could certainly have a cast iron beam made that is roughly the same size and weighs 25 lbs/ft.  ask that same engineer if he thinks the beam on its side will have lateral torsional problems since it is being loaded on its weak axis...  
thanks everyone. engineer of record just wanted the contractor to take the beam off its weak axis from what the second engineer said, it should be no problem loading this beam on its weak axis. it seems the from all your posts that this is true. my contractor decided just the same to rotate the beam off its weak axis mainly because he will need a structural op signed off by the same engineer before the city final.
best regards everyone,
dacgrp
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