How to calculate Beta-W for unequal angle legs

[iestructural]

Hi all,

I've been working on how to calculate the Lateral Torsional Buckling capacity of unrestrained single angles using the major and minor principal axes and ran into a bit of a snag. My calculus is quite a bit rusty and in order to calculate the capacity of angles with unequal legs via AISC equation F10-5 (14th edition page 16.1-61) I need to evaluate an integral given in the commentary at the bottom of Table C-F10.1 on page 16.1-322 so I can figure out this β_w. Has anyone successfully done this either numerically or otherwise? If you have may I trouble you for an example where it was correctly done? Attached is my current spreadsheet for angle property calculations.

 

[Celt83]

found this resource awhile ago, hopefully helpful.

Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

 

[WARose]

I need to evaluate an integral given in the commentary at the bottom of Table C-F10.1 on page 16.1-322 so I can figure out this βw. Has anyone successfully done this either numerically or otherwise?

Why calculate it when it is given in the commentary for each shape? (p.16.1-284 in the 13th ed.)

 

[iestructural]

It's not given for custom size shapes like bent plates that are similar to angles. The point of calculating it is to have a spreadsheet that can handle the generic case.

 

[WARose]

I don't know that I would be using AISC for a design check of cold formed steel. That would fall (I think) more into AISI's territory.

 

[iestructural]

These aren't light gauge cold-formed members. They're bent plates made out of A36 steel. Usually 1/4" thick or thicker.

 

[WARose]

At least the last time I looked (and granted, I’m always a code or two behind) AISI’s code is still applicable for 1” thickness or less. (And that includes ASTM A36 steels.)