Load Path / Eccentricities 4

[slickdeals]

Folks,
This is not a design for a real project and merely a hypothetical question.

The sketch shows two options. Option B is what is probably always modeled in analysis (centroids are coincident). But more than likely, the detail provided in the drawing is Option A.

I believe AISC lets you ignore connection eccentricities in statically loaded members (J1.7). I am not sure if this qualifies for the same.

I am presuming that based on the gusset geometry, it is impossible (or very difficult) to get enough weld to transmit the moment due to eccentricity (weak-axis bending of gusset). In that case, the WT member will have to be sized up to pick up axial + moment at the end connection. Am I right in stating this?

How would you folks approach such a problem? I am not trying to make it a research problem (maybe it is), but get an idea on how one would go about designing such a connection.

Thanks in advance.

 

[BAretired]

The total moment at the joint is P*e. If the gusset is very stiff and is connected to a stiff column and beam or baseplate, it will carry part of the moment while the WT carries the remainder. If the WT is designed for a tension of P and a moment of P*e, it doesn't matter how much moment is carried by the gusset.

If you are really interested in how the moment is shared, you must do a strain compatibility analysis.

BA

 

[paddingtongreen]

An interesting side bar is to look at the Tee stem (I had to review a failure, not our design, and the boss insisted that I look at everything). When the Tee is in tension, in this connection, the stem is often in compression; when the Tee is in compression, the stem is often in tension.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[slickdeals]

Folks,
I had contacted Dr. Bill Thornton and he was really kind enough to provide his input. Consummate professional, indeed!!!

He informed me that the 2010 specs won't include the "don't consider eccentricities if U>0.6" because it is incorrect. In addition, he concurs with most of the discussion here for designing the WT for axial + moment and designing the bolts for shear only.

Please see his notes on the issue which I am sharing here.

 

[JAE]

Appreciate the info slickdeals. Thanks.