Design of Double Angle Connections 1

[BS8110]

Folks,

I have a beam to column connection using double angles. The angles are bolted to the column flange and welded to the beam web.

The beam has an axial tension force aswell as shear.

Section 9 of the steel construction manual (page 9-10) provides a formula for minimum angle thickness to eliminate prying action.

My question is, does the angle leg need to be checked for bending (due to axial tension in beam)when having determined the min angle leg thickness using the formula?

I presume that the angle needs to be checked for bending using yield stresses (Fy) and not ultimate stress (Fu) as in the formula.

thanks for reading

 

[DaveAtkins]

If you make the angles thick enough to eliminate prying, then you need not check bending of the angle legs. The thickness of the angle legs combined with pretension in the bolts minimizes bending.

But don't make the angles thicker than 5/8", because then it will not be a pinned connection for gravity loads.

DaveAtkins

 

[nutte]

The check on page 9-10 does check the angle legs for bending under tension load. It just isn't apparent when looking at the final form of the equation.

Plastic modulus of angle leg Z = p tmin^2 / 4

Moment on angle leg = T b'

LRFD permissible moment = 0.9 Fu Z (Fu being used in this case I believe because it matches up better with tested values)

T b' = 0.9 Fu p tmin^2 / 4

Solve for tmin, and you get the equation on page 9-10. (LRFD) tmin = [4.44 T b' / (p Fu)]^0.5

 

[Den32]

Agree with posts above, AISC equation already considers this.

Don't forget to check bolts for COMBINED forces (Tension & Shear), and the WELDS for the skewed shear load.