Steel angles

[ab21]

Hi,

I have been working in transmission industry for a few months. They use steel angles, single and double angles, a lot in this industry. I have a few questions which I would appreciate if you could answer as I cannot get my head around it. How does compression capacity of the member change when there are two members connected as double angles, short or long flange connected?
What about bending? As i understand it you will have to resolve it in its principle axes v-v (major axis) and u-u (minor axis)?

If you have any useful reading material i would appreciate it if you could share it, if there is worked example of how to calculate compression and bending capacity of single and double angles? I lack knowledge in basic design of angles and cannot find useful material online.

Thanks

 

[Triangled]

yea, angles are weird, precisely because of the "w" axis "z" axis bending, ie principle axes. this guy helped me...

http://www.lulu.com/shop/whitney-mcnulty/single-angle-design-manual/paperback/product-6241104.html

in my mind, when you double the angles, you are potentially in effect removing the "w" and "z" axes from consideration...but this depends on their connection. if back to back fully welded adequately connected, then you have only 2 axes of bending, "x" and "y". if backs are separated, say by an inch, then the angles tend to bend sort of towards each other or sort of away from each other about the weak principle axis.

 

[KootK]

I second the McNulty book. Good stuff.

I'd also point you to this reference which you surely must already have kicking around your office: ASCE 10

How does compression capacity of the member change when there are two members connected as double angles, short or long flange connected?

- For buckling in a direction perpendicular to the mated surface, flexural stiffness and buckling resistance increase dramatically if the members are connected such that they can be relied upon to act compositely.

- For buckling in a direction parallel to the mated surface, you basically get 2X the original capacity.

- For torsional buckling modes, you've basically got a Tee section rather than an angle or pair of angles. Still crappy but less so.

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.