CFS Web Stiffeners

[BSVBD]

The roof has a 96 PSF snow drift load.

The 10x162x12 gage roof purlins I have sized have a total reaction of 1,300 LBS.

How do you know if you need web stiffeners at the end bearing?

Following an SSMA Product Technical Information guide, the Web Crippling Load Tables show an Allowable Web Crippling Load of 2,396 LBS for 3.5" bearing. However, Note #1 says, "Only members with stiffened flanges are considered."

If that is the case, how, then, do I determine the allowable load for an UNstiffened member?

I have no problem specifying web stiffeners, but, I want to be efficient and wise. I don't want to stiffen the webs if not necessary.

Thank you!

 

[EngineeringEric]

Are the flanges stiffened? i think the little lip on the end of the flange is the stiffener lip (i may be wrong)

 

[BSVBD]

It IS a "CEE" shape with 0.500" Lip. Is THAT what is meant by a stiffened flange?

 

[MacGruber22]

Yes, the lip stiffens the flange.

How do you know if you need web stiffeners at the end bearing?

Calculate the buckling capacity of the web via the AISI specifications. They are FREE @

http://www.cfsei.org/free-publications

"It is imperative Cunth doesn't get his hands on those codes."

 

[RPMG]

You're section is 1000S162-97 where "S" stands for stiffened flange.

 

[KootK]

I agree with the posts above. Obviously, the web depends on the stiffening influence of the the flanges. However, it seems that the in plane flexure induced in the flanges by the very act of bracing the web would cause the flanges themselves to buckle were they not edge braced by the stiffening lips.

Frankly, I sometimes question our reliance on such slender elements. If a fairy stepped on a 1 mm flange lip and it straightened, apparently Armageddon would ensue. No problems in the field that I am aware of however.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.