Double Angles in Bending - Whats the allowable stress?

[marinaman]

I have a pair of double angles subject to bending moment.

The angles are 10'-6" long and are seperated by 5/8". The angles are fully unbraced. They are subject to moment about their X-X axis.

The angles are 6" x 6" x 5/8" angles.

Can someone guide me to a reference that will help me to calculate the allowable bending stress in these angles?

 

[Stillerz]

AISC 360-05, Ch F.9

 

[Stillerz]

page 16.1-57 of the 2005 spec

 

[rb1957]

each angle would react 1/2 the applied moment.

if the angles are unbraced, is the moment introduced (and reacted) at the ends ?

i would suspect that mid-span the angles would be bending about their principal axes, but the ends Could be restrained to bend about the x-x axis, creating another load to be considered at the interface.

 

[Stillerz]

bending capacity will be based on yeilding, LTB, or FLB...assuming the "stems" of your double angle are always in tension.

 

[Stillerz]

keep in mind, if this member is carrying some axial load as well, you'll want to reference Chapter G of 360-05 for combined forces.

 

[marinaman]

Stillerz,

Can you reference me to a text that references allowable stress instead of a LRFD method?

 

[BAretired]

Allowable stress is not a suitable method, or at least, if it is, must be based on ultimate behavior.

BA

 

[Stillerz]

the 13th edition of AISC is ASD/LRFD

 

[JStephen]

"Specifification for Allowable Stress Design of Single-Angle Members" is in the back of the old 9th Ed. green-cover AISC-ASD books.