eccentric block shear

[pperlich]

See attached image.

The two tabs are welded to the flanges as shown.

They are loaded parallel to the length of the beam.

I have calculated the eccentric weld group for each tab.

How do check that the beam's flange isn't over stressed? It seems that I need to check for an eccentric block shear condition, if that make any sense. I'm using AISC 14th Ed.

Thank you!

 

[WARose]

How do check that the beam's flange isn't over stressed?

Me personally, I'd check the stress at the flange using a allowable of 0.6Fy (for tension/comp. perpendicular to the flange) and 0.4Fy as my allowable for shears.

You'd superimpose those ratios on top of weak axis & torsional stresses and see that it's less than unity.

I'd probably have a stiffener (or 2) with that set up as well.

 

[pperlich]

Does the AISC spec have a method of evaluating eccentric block shear?

 

[WARose]

I've never even heard the term "eccentric block shear". (And I've been at this for quite a while.) I suppose you could use a block shear approach......but what I was talking about really simplifies things (from the standpoint of checking combined stresses, which would be important here).

 

[pperlich]

I'm sure you're right, I'm just an ME with very limited exposure to the AISC spec.

Whilst googling I came across this article (attached). I need to finish reading it, but maybe you'll find it interesting. Thanks for the help. Page 6 of the PDF looks about like what I'm thinking about, except I'm welding, not bolting.

 

[BridgeSmith]

If your sketch is anything close to accurate regarding the position of the bolt holes, block shear failure is far being critical. Your edge distance and bearing at the individual bolt holes (failure by tearing the flange out at the bolt holes) could be, although you'd presumably have to shear the bolts on one side for the ones on the other side to tear out. That also would not seem to be a critical failure mode, given the small eccentricity to the line of force.

 

[WARose]

Whilst googling I came across this article (attached). I need to finish reading it, but maybe you'll find it interesting. Thanks for the help. Page 6 of the PDF looks about like what I'm thinking about, except I'm welding, not bolting.

Figure 3 in that paper is kind of how I was talking about treating it (in my first post). I don't agree with that distribution in the last figure on the right though. Seems to me like it would be triangular.