Can Angles be used as beams? 3

[Anne651]

I am not sure if Angles can take moment, and therefore
act as beams.

But I have seen angles used as a holder for windows or studs.

Can angles take uniform load (moment) then?

Thanks

 

[JAE]

Yes, they can.

 

[Anne651]

But how? Mr=phi * S * Fy if it is class 1,2,3?

 

[csd72]

What code are you using?

 

[Anne651]

I mean can single angle take moment?

 

[Anne651]

The Steel Handbook, S16

 

[WpgKarl]

As long as it can't buckle laterally (comp. flange is braced) then you can use Mr = phi*S*Fy, but if it can buckle then you need to consider the twisting caused by the load being applied off of the shear centre of the angle, and use the principal axes to check the point at which the stress reaches the yield stress, at one of the corners of the angle.

Using S16, must be a Canadian, eh?

 

[Anne651]

Everything makes sense until, "Use the principal axes to check the point at which the stress reaches the yield stress."

How to use the axes of rotation to check the point of yielding stress. Even if I have the point where it will yields, what purpose does it serve? How am I getting a laterally unsupported moment?

 

[JStephen]

"How am I getting a laterally unsupported moment?"

By any chance, are you getting an error message in design software relating to an angle? That's what that line sounds like. If so, more detail on what is actually going on would be helpful.

 

[msquared48]

"How am I getting a laterally unsupported moment?"

You are not laterally supporting the moment, but the compression flange of the angle that is resisting the moment. Angles are used to resist forces all the time. No worries.

Mike McCann
MMC Engineering

 

[civeng80]

To answer your question!

Angles can be used as beams.
Its a little bit more difficult to analyse them because of biaxial stresses because they are not symetrical. Thats why theres Principle axis.

It would be alot easier to look up safe load tables for your region particularly if they are only lightly loaded e.g. used as lintels over windows.

Cheers !

 

[rb1957]

that would be "Principal" ... geez

 

[csd72]

If the angle is continuously laterally supported then you can get away with only analysing it under vertical bending.

 

[JAE]

Check out page 57 of this document (section F10):

http://www.aisc.org/Content/Content...fication/2005Specification_third_printing.pdf

This is the newer AISC spec for single angle design.

 

[msquared48]

Theoretically, if the load goes thru the intersection of the principle axes, then there is no torsion, but show me where that is going to happen in the real world. Those little load gremlins have a mind of their own.

Mike McCann
MMC Engineering

 

[Ussuri]

There will be no torsion generated if the load passes through the shear centre (flexural center in Roark's). For unsymmetric sections the shear centre is not in the same place as the centroid.

 

[msquared48]

Yes, you're right. Sorry bout dat...

Guess I don't worry about angles in torsion too often...

Mike McCann
MMC Engineering

 

[RareBugTX]

Neither me, I do not worry about torsion for short spans, windows, doors etc. Just a waste of brain. For more serious or critical loads, just go with wide flange beams and try not to create unsymmetrical loading. Make it easy to build, easy to analyse.

My two cents.

Regards,

Chicago Rarebug